Fix permissions of /var/lib/tabacco-metadb on first run

roles/float-base-backup-metadata/tasks/main.yml

@@ -13,6 +13,16 @@
     system: yes
     state: present
 
+# The directory is already created by the dataset, but we need
+# to ensure the permissions are correct or the first ansible run
+# will fail (breaking tests).
+- name: Create backup metadata server database dir
+  file:
+    path: /var/lib/tabacco-metadb
+    state: directory
+    owner: backup-metadata
+    mode: 0700
+
 - name: Configure the backup metadata server
   template:
     src: metadb.yml.j2