Fix total documents in Elasticsearch / Admin Center

The number of document displayed in Admin Center/ Elasticsearch / Info
is the total number of document in the first node of the cluser.
This number include all documents for all the shards present in the node.

This number can be bigger than the Nuxeo documents if there are other index present in the node,
this number can be lower than the Nuxeo documents if all the shards are not present on the first node.
This number is correct only if the Nuxeo index is the only index on the cluster and all the shards are located on the first node.

Also we should not display cluster or nodes information by default.

Fixed by adding a property elasticsearch.adminCenter.displayClusterInfo false by default, always true when using embedded mode.