Enable the Nova V3 API Tests

Re-enables the tests which were temporarily disabled
to help debug issues with the gate.

Don't approve this until https://review.openstack.org/#/c/57572/
and https://review.openstack.org/#/c/57584/ have merged
and the gate looks stable

Change-Id: I049360bc8409e666852911404b1c7c8e12364745
Merge "Enable the Nova V3 API Tests"