Update config option for collecting sensor data
Update config option for collecting sensor data

This patch updates the notification driver option for collecting sensor
data because [DEFAULT]/notification_driver is deprecated and
'messaging' driver should only be used in cases where there are existing
consumers deployed which do not support the 2.0 message format.

Change-Id: Ia6c55149e5cb12d1201742f7008047e35570b410

openstack/ironic,openstack/ironic