TripleO jobs: Replace CentOS 8 jobs by CentOS 9 jobs

Now TripleO team is replacing CentOS 8 jobs in master by CentOS 9 jobs.
This follows that and replaces tripleo jobs in puppet repos to switch
to CentOS 9.

Depends-on: https://review.opendev.org/828525
Change-Id: Ic9c5eade3ef0d851cb21c3e4d6b53efef83d6a22

.zuul.yaml

@@ -14,7 +14,7 @@
 
 - job:
     name: puppet-keystone-tripleo-standalone
-    parent: tripleo-puppet-ci-centos-8-standalone
+    parent: tripleo-puppet-ci-centos-9-standalone
     description: |
       TripleO standalone Job running Identity specific Tempest tests.
     vars: