Use command instead of debug for handlers

Due to the debug message plugin the handler restart
messages show at the end of the playbook execution
which is a little confusing. Using debug also
requires setting changed_when to true which is a
little extra bit of code which we do not have to
carry.

Instead we use the command module which is simple,
works and less wordy.

Change-Id: I5d4573e5415365fcd493850192f90a46897d6534

handlers/main.yml

@@ -14,9 +14,7 @@
 # limitations under the License.
 
 - name: Restart gnocchi services
-  debug:
-    msg: "Restarting services"
-  changed_when: true
+  command: "/bin/true"
   notify:
     - Stop services
     - Copy new policy file into place