(Re-)enable vnc console tests in nova-multi-cell job
(Re-)enable vnc console tests in nova-multi-cell job

This reverts commit 47b73030cba7d67fe308c5b89c2a64e93d74bcd6.

The dependent devstack change fixes the issue so we can enable
vnc console tempest testing in the nova-multi-cell job.

Depends-On: https://review.opendev.org/661391/

Change-Id: Iad71b6e15bb91e51080cd9f940410dc9af791963
Related-Bug: #1830417

openstack/nova,klmitch/nova,rahulunair/nova,mahak/nova,mahak/nova,klmitch/nova,openstack/nova,rahulunair/nova,klmitch/nova,klmitch/nova,mahak/nova,openstack/nova,rahulunair/nova