Updates to the tempest-tripleo-ui plugin
Updates to the tempest-tripleo-ui plugin

The plugin moved to an internal repo and will be included by passing
an appropriate --plugin parameter from the job. Removing the plugins
part from plugins/tempest/vars/tests/tripleo_ui.yaml.

Change-Id: I4d24ac827ffb73bf66d679ffbc68d20cbc22452a

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