Make broken tempest-full-py3-opensuse15 job only until stable/xena

tempest-full-py3-opensuse15 is failing all the time and
opensuse is not tested/supported distro in testing runtime
or devstack anymore. These job is removed from master gate
but it is in use until stable/xena.

- https://review.opendev.org/q/topic:%22remove-tempest-full-py3-opensuse15%22+(status:open%20OR%20status:merged)

Modifying it for until stable/xena only.

Change-Id: Ibe9166091011c08644cba783b7db77124cb17417
3 files changed