Move zuul jobs layout to centos9 only for master branch
Move zuul jobs layout to centos9 only for master branch

See topic branch [1] for related reviews.

[1] https://review.opendev.org/q/topic:c8_teardown_master
Depends-On: https://review.opendev.org/c/openstack/tripleo-ci/+/826317

Change-Id: I3e944fa960242c2c30f4921863f3934a4084150b

openstack/python-tripleoclient