Add victoria/wallaby stable branch jobs on master gate

We have stable/victoria and stable/wallaby released so we
should add their job on master gate to keep branchless
tempest plugins compatible to those branch.

This also removes the stable/stein job as that is in EM
state now.

Ref: Tempest plugins guide for stable branch testing:
- https://docs.openstack.org/tempest/latest/stable_branch_testing_policy.html

Change-Id: Ic60d898969e730fcf1aebc4d103f06ec0baf24ed
1 file changed