[virsh] Only quiesce cinder-backup if it is there
[virsh] Only quiesce cinder-backup if it is there

If cinder-backup was never deployed, then it is not possible
for it to ever be up. In this patch we first check to see if
the service exists before we check whether it is up.

JIRA: UPG-3103

Change-Id: I7915ffee16fc2b96d48f1e70db81ae4a80173c9b

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