Get local backend name from config

lib/blogs.php

@@ -76,8 +76,8 @@ function noblogs_get_backend_map() {
 
 // Return the backend ID for the local host.
 function noblogs_get_local_backend_id() {
-  $id = trim(file_get_contents("/etc/ai/public_id"));
-  return "backend_{$id}";
+  global $noblogs_config;
+  return $noblogs_config['local_backend_name'];
 }
 
 // Return a list of blogs that are local to this server.