Stop accidentally removing docker-distribution

By default Puppet does virtual package matching if precise name matching
fails. Docker-distribution RPM "provides" docker-registry:

bash-4.2# rpm -q --whatprovides docker-registry
docker-distribution-2.5.1-1.el7.x86_64

This means that when we wanted to make docker-registry package absent,
we were actually removing docker-distribution instead. This is now fixed
by allow_virtual => false. Only name matching is performed.

Related BZ: https://bugzilla.redhat.com/show_bug.cgi?id=1428826

Change-Id: I1f93b404085f0bc2b6c063f573c801db6409c0bb
Closes-Bug: #1666459
(cherry picked from commit d12c004bc9)

manifests/profile/base/docker_registry.pp

@@ -37,7 +37,8 @@ class tripleo::profile::base::docker_registry (
 ) {
   # We want a v2 registry
   package{'docker-registry':
-    ensure => absent,
+    ensure        => absent,
+    allow_virtual => false,
   }
   package{'docker-distribution': }
   package{'docker': }