Use user specified private key when deleting temp keys
Use user specified private key when deleting temp keys

We use the user specified private key when we inject the temporary ssh
key, and we should also use it when we delete the temprorary ssh keys.
Even though this script is no longer used on master, we should commit
this so we can backport to queens.

Change-Id: Id389984b87209f959e4cf439abd8165a3a08ead3
Closes-Bug: #1773980

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