Fix Grafana dashboards

In commit ae50318d some modified dashboards were exported using the
wrong method, which resulted in the classic DS_LOCALHOST errors.

roles/prometheus/files/grafana/dashboards/host.json

 {
-  "__inputs": [
-    {
-      "name": "DS_LOCALHOST",
-      "label": "localhost",
-      "description": "",
-      "type": "datasource",
-      "pluginId": "prometheus",
-      "pluginName": "Prometheus"
-    }
-  ],
-  "__requires": [
-    {
-      "type": "grafana",
-      "id": "grafana",
-      "name": "Grafana",
-      "version": "6.1.6"
-    },
-    {
-      "type": "panel",
-      "id": "graph",
-      "name": "Graph",
-      "version": ""
-    },
-    {
-      "type": "datasource",
-      "id": "prometheus",
-      "name": "Prometheus",
-      "version": "1.0.0"
-    }
-  ],
   "annotations": {
     "list": [
       {
@@ -71,7 +41,7 @@
       "bars": false,
       "dashLength": 10,
       "dashes": false,
-      "datasource": "${DS_LOCALHOST}",
+      "datasource": "localhost",
       "decimals": 0,
       "description": "See $cluster",
       "editable": true,
@@ -185,7 +155,7 @@
       "bars": false,
       "dashLength": 10,
       "dashes": false,
-      "datasource": "${DS_LOCALHOST}",
+      "datasource": "localhost",
       "description": "",
       "editable": true,
       "error": false,
@@ -334,7 +304,7 @@
       "bars": false,
       "dashLength": 10,
       "dashes": false,
-      "datasource": "${DS_LOCALHOST}",
+      "datasource": "localhost",
       "editable": true,
       "error": false,
       "fill": 1,
@@ -477,7 +447,7 @@
       "bars": false,
       "dashLength": 10,
       "dashes": false,
-      "datasource": "${DS_LOCALHOST}",
+      "datasource": "localhost",
       "editable": true,
       "error": false,
       "fill": 1,
@@ -652,7 +622,7 @@
       "bars": false,
       "dashLength": 10,
       "dashes": false,
-      "datasource": "${DS_LOCALHOST}",
+      "datasource": "localhost",
       "editable": true,
       "error": false,
       "fill": 0,
@@ -781,7 +751,7 @@
       "bars": true,
       "dashLength": 10,
       "dashes": false,
-      "datasource": "${DS_LOCALHOST}",
+      "datasource": "localhost",
       "editable": true,
       "error": false,
       "fill": 1,
@@ -886,7 +856,7 @@
       "bars": false,
       "dashLength": 10,
       "dashes": false,
-      "datasource": "${DS_LOCALHOST}",
+      "datasource": "localhost",
       "decimals": 0,
       "editable": true,
       "error": false,
@@ -1021,7 +991,7 @@
       "bars": true,
       "dashLength": 10,
       "dashes": false,
-      "datasource": "${DS_LOCALHOST}",
+      "datasource": "localhost",
       "editable": true,
       "error": false,
       "fill": 1,
@@ -1146,7 +1116,7 @@
       "bars": false,
       "dashLength": 10,
       "dashes": false,
-      "datasource": "${DS_LOCALHOST}",
+      "datasource": "localhost",
       "fill": 1,
       "gridPos": {
         "h": 7,
@@ -1260,7 +1230,7 @@
       "bars": true,
       "dashLength": 10,
       "dashes": false,
-      "datasource": "${DS_LOCALHOST}",
+      "datasource": "localhost",
       "fill": 1,
       "gridPos": {
         "h": 7,
@@ -1436,7 +1406,7 @@
       "bars": false,
       "dashLength": 10,
       "dashes": false,
-      "datasource": "${DS_LOCALHOST}",
+      "datasource": "localhost",
       "fill": 1,
       "gridPos": {
         "h": 7,
@@ -1559,7 +1529,7 @@
       "bars": false,
       "dashLength": 10,
       "dashes": false,
-      "datasource": "${DS_LOCALHOST}",
+      "datasource": "localhost",
       "fill": 1,
       "gridPos": {
         "h": 7,
@@ -1680,7 +1650,7 @@
       "bars": false,
       "dashLength": 10,
       "dashes": false,
-      "datasource": "${DS_LOCALHOST}",
+      "datasource": "localhost",
       "fill": 1,
       "gridPos": {
         "h": 7,
@@ -1803,7 +1773,7 @@
       "bars": false,
       "dashLength": 10,
       "dashes": false,
-      "datasource": "${DS_LOCALHOST}",
+      "datasource": "localhost",
       "editable": true,
       "error": false,
       "fill": 0,
@@ -1923,7 +1893,7 @@
       {
         "allValue": null,
         "current": {},
-        "datasource": "${DS_LOCALHOST}",
+        "datasource": "localhost",
         "definition": "",
         "hide": 0,
         "includeAll": false,
@@ -1977,4 +1947,4 @@
   "title": "Host overview",
   "uid": "W8eE_Qgik",
   "version": 2
-}
\ No newline at end of file
+}

roles/prometheus/files/grafana/dashboards/http.json

 {
-  "__inputs": [
-    {
-      "name": "DS_LOCALHOST",
-      "label": "localhost",
-      "description": "",
-      "type": "datasource",
-      "pluginId": "prometheus",
-      "pluginName": "Prometheus"
-    }
-  ],
-  "__requires": [
-    {
-      "type": "grafana",
-      "id": "grafana",
-      "name": "Grafana",
-      "version": "6.1.6"
-    },
-    {
-      "type": "panel",
-      "id": "graph",
-      "name": "Graph",
-      "version": ""
-    },
-    {
-      "type": "datasource",
-      "id": "prometheus",
-      "name": "Prometheus",
-      "version": "1.0.0"
-    }
-  ],
   "annotations": {
     "list": [
       {
@@ -54,7 +24,7 @@
       "bars": false,
       "dashLength": 10,
       "dashes": false,
-      "datasource": "${DS_LOCALHOST}",
+      "datasource": "localhost",
       "fill": 1,
       "gridPos": {
         "h": 6,
@@ -139,7 +109,7 @@
       "bars": false,
       "dashLength": 10,
       "dashes": false,
-      "datasource": "${DS_LOCALHOST}",
+      "datasource": "localhost",
       "fill": 1,
       "gridPos": {
         "h": 6,
@@ -225,7 +195,7 @@
       "bars": false,
       "dashLength": 10,
       "dashes": false,
-      "datasource": "${DS_LOCALHOST}",
+      "datasource": "localhost",
       "fill": 1,
       "gridPos": {
         "h": 6,
@@ -310,7 +280,7 @@
       "bars": false,
       "dashLength": 10,
       "dashes": false,
-      "datasource": "${DS_LOCALHOST}",
+      "datasource": "localhost",
       "fill": 0,
       "gridPos": {
         "h": 6,
@@ -415,7 +385,7 @@
       {
         "allValue": ".*",
         "current": {},
-        "datasource": "${DS_LOCALHOST}",
+        "datasource": "localhost",
         "definition": "",
         "hide": 0,
         "includeAll": true,

roles/prometheus/files/grafana/dashboards/network.json

 {
-  "__inputs": [
-    {
-      "name": "DS_LOCALHOST",
-      "label": "localhost",
-      "description": "",
-      "type": "datasource",
-      "pluginId": "prometheus",
-      "pluginName": "Prometheus"
-    }
-  ],
-  "__requires": [
-    {
-      "type": "grafana",
-      "id": "grafana",
-      "name": "Grafana",
-      "version": "6.1.6"
-    },
-    {
-      "type": "panel",
-      "id": "graph",
-      "name": "Graph",
-      "version": ""
-    },
-    {
-      "type": "datasource",
-      "id": "prometheus",
-      "name": "Prometheus",
-      "version": "1.0.0"
-    }
-  ],
   "annotations": {
     "list": [
       {
@@ -59,7 +29,7 @@
       "bars": false,
       "dashLength": 10,
       "dashes": false,
-      "datasource": "${DS_LOCALHOST}",
+      "datasource": "localhost",
       "fill": 0,
       "gridPos": {
         "h": 6,
@@ -144,7 +114,7 @@
       "bars": false,
       "dashLength": 10,
       "dashes": false,
-      "datasource": "${DS_LOCALHOST}",
+      "datasource": "localhost",
       "fill": 0,
       "gridPos": {
         "h": 6,
@@ -230,7 +200,7 @@
       "bars": false,
       "dashLength": 10,
       "dashes": false,
-      "datasource": "${DS_LOCALHOST}",
+      "datasource": "localhost",
       "fill": 0,
       "gridPos": {
         "h": 6,
@@ -326,7 +296,7 @@
       "bars": false,
       "dashLength": 10,
       "dashes": false,
-      "datasource": "${DS_LOCALHOST}",
+      "datasource": "localhost",
       "fill": 0,
       "gridPos": {
         "h": 6,
@@ -411,7 +381,7 @@
       "bars": false,
       "dashLength": 10,
       "dashes": false,
-      "datasource": "${DS_LOCALHOST}",
+      "datasource": "localhost",
       "fill": 0,
       "gridPos": {
         "h": 6,
@@ -496,7 +466,7 @@
       "bars": false,
       "dashLength": 10,
       "dashes": false,
-      "datasource": "${DS_LOCALHOST}",
+      "datasource": "localhost",
       "fill": 0,
       "gridPos": {
         "h": 6,
@@ -592,7 +562,7 @@
       "bars": false,
       "dashLength": 10,
       "dashes": false,
-      "datasource": "${DS_LOCALHOST}",
+      "datasource": "localhost",
       "fill": 1,
       "gridPos": {
         "h": 6,