Ensure rsync is installed for fernet rotation

The patch ensures that rsync package is installed
by linux.system state prior to keystone state invocation
which will fail in case rsync is not installed

Change-Id: Iff796a1aa84c32a4a0d4f13f7cf8a8775b99dbbe
Related-PROD: PROD-23382
diff --git a/keystone/server/fernet_rotation/cluster.yml b/keystone/server/fernet_rotation/cluster.yml
index 7da8b5b..c34c4f8 100644
--- a/keystone/server/fernet_rotation/cluster.yml
+++ b/keystone/server/fernet_rotation/cluster.yml
@@ -24,6 +24,9 @@
         credential_rotation_driver: ${_param:credential_rotation_driver}
   linux:
     system:
+      package:
+        rsync:
+          version: latest
       cron:
         user:
           keystone: