Fix placement of ssh public key

The ssh public key should be in ~/.ssh folder instead of at the root
of the user's home folder.

Change-Id: I29c8f068b8765e79439cb5f74f77618c12d6ef4a

manifests/init.pp

@@ -655,7 +655,7 @@ class gerrit(
   }
 
   if $ssh_replication_rsa_pubkey_contents != '' {
-    file { '/home/gerrit2/id_rsa.pub':
+    file { '/home/gerrit2/.ssh/id_rsa.pub':
       owner   => 'gerrit2',
       group   => 'gerrit2',
       mode    => '0644',