Reduce elasticsearch retention to 7 days

We were keeping 10 days of logs in elasticsearch but now that we've
caught up on the job backlog that has filled the disks on our
elasticsearch cluster. Address this by reducing log retention by 30%.

Change-Id: I8b1e126e08eb4745d01534a63c558bf1494ac6bf

modules/openstack_project/manifests/elasticsearch_node.pp

@@ -50,7 +50,7 @@ class openstack_project::elasticsearch_node (
   }
 
   class { 'logstash::curator':
-    keep_for_days  => '10',
+    keep_for_days  => '7',
   }
 
 }