Added retries for db_sync

If db sync fails, it is never retried leading to errors. So, this
patch adds retries for db_sync to avoid sync fails.

Change-Id: I836b56d125ec781f24b5ea1797ac882b353e2379
Related-Bug: #1628580
Closes-Bug: #1645474
(cherry picked from commit 9e7ed558f2)

manifests/db/sync.pp

@@ -26,6 +26,8 @@ class neutron::db::sync(
     command     => "neutron-db-manage ${extra_params} upgrade head",
     path        => '/usr/bin',
     refreshonly => true,
+    try_sleep   => 5,
+    tries       => 10,
     logoutput   => on_failure,
   }
 }