[UPGRADES] Use import_role during UC version discovery.
[UPGRADES] Use import_role during UC version discovery.

We need to manipulate list of tags to get correct tasks executed
for undercloud upgrade.

Change-Id: I6b52dc03571733ee0abaff414248f54eedb8f8db

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