tempest/layer4: explicitly enable Sahara and Trove
tempest/layer4: explicitly enable Sahara and Trove

The devstack default does not clone sahara and trove by default
anymore.

Change-Id: I787944217b8cfa856aae3af4a9fad0deb4d4cac5

openstack-infra/project-config,openstack-infra/project-config