With victoria branched, use it for stable release and move ussuri to
previous stable release.
This is already prepared to upcoming changes in victoria:
* switch to victoria neutron-tempest-plugin template
https://review.opendev.org/#/c/756585/
* not listing *master* jobs being dropped in
https://review.opendev.org/#/c/756695/
Change-Id: I861169977053d5c73b8edc41dae78e5acc9c339d