Fix log update-status error

This patch adds a dummy update_status function so that the update-status
hook 'has' a function to run and thus silence the log error.

Change-Id: I96dfba233b98da60d8c138b84e8249cdda109563
Closes-bug: #1837639

hooks/ceilometer_hooks.py

@@ -160,6 +160,12 @@ def amqp_joined(relation_id=None):
                  vhost=config('rabbit-vhost'))
 
 
+@hooks.hook('update-status')
+def dummy_update_status():
+    """Dummy function to silence missing hook log entry"""
+    pass
+
+
 @hooks.hook('amqp-relation-changed',
             'amqp-relation-departed')
 @restart_on_change(restart_map())