Run designate pool update only on bootstrap node

If this is run on all nodes it can cause collisions while updating
the database.

Change-Id: I1dcb28aac111189eec142c6b4c8879431f72094b

docker/services/designate-central.yaml

@@ -150,14 +150,14 @@ outputs:
             net: host
             privileged: false
             detach: false
-            user: designate
+            user: root
             volumes:
               list_concat:
                 - {get_attr: [ContainersCommon, volumes]}
                 -
                   - /var/lib/config-data/designate/etc/designate/:/etc/designate/:ro
                   - /var/log/containers/designate:/var/log/designate
-            command: "/bin/designate-manage pool update"
+            command: "/usr/bin/bootstrap_host_exec designate_central su designate -s /bin/bash -c '/bin/designate-manage pool update'"
       host_prep_tasks:
         - name: create persistent logs directory
           file: