Only wait for UC to go down when we're really rebooting
Only wait for UC to go down when we're really rebooting

The reboot task is guarded by "update is changed" condition, but
waiting for the node to go down isn't guarded this way, so we used to
wait for undercloud to go down even when it wasn't rebooting. This is
now fixed by adding the "update is changed" condition to the waiting
task too.

Change-Id: I65d1bd08b9ec805bc766419d410748e2bea95846

redhat-openstack/infrared,redhat-openstack/infrared,redhat-openstack/infrared