Add sanity checks for xinetd service restart.
Add sanity checks for xinetd service restart.

xinetd.service is not installed on pre-provisioned nodes,
 so we'll add extra check for its restart.

Change-Id: I4fbac81ceb4aba534395cf8c0a842fb732559234
Closes-Bug: 1775154

dprince/tripleo-heat-templates,openstack/tripleo-heat-templates,openstack/tripleo-heat-templates,dprince/tripleo-heat-templates