instance.update notifications don't always identify the service

instance_update in conductor/manager.py doesn't identify the service
when calling notifications.send_update(), resulting in mesages on the
notification queue having a service value of None.

This change makes sure that the correct service is identified even
when running conductor in local mode

Change-Id: I1b22c0b46040f51ba715a4d9fa19ef4c98359070
Merge "instance.update notifications don't always identify the service"