Add Tempest gate job for stable/zed

Now we have stable/zed branch ready for devstack and so does
for all service projects.

This commit adds the Tempest testing for stable/zed by adding
new jobs running on stable/zed version of openstack.

Change-Id: I6a331a6f2466aa4e4d9f607660b87fa60a63bf4b
2 files changed