keystone: run credential setup on xenial
keystone: run credential setup on xenial

The credential configuration was not packaged back in Newton,
it's now here and we can test it now.

Change-Id: I95a7490e3ed7f781d4cecfe15754432834a7c812

openstack/puppet-openstack-integration,openstack/puppet-openstack-integration,openstack/puppet-openstack-integration