Replace litmus jobs to CentOS Stream 9 (but non-voting)

Some projects (Oslo, Nova, Cinder, ...) removed support for Python 3.6
and no longer work with CentOS 8 Stream which has Python 3.6.

This change migrates the litmus jobs to CentOS Stream 9 because of that
and teardown of CentOS 8 Stream packages in RDO.

Unfortunately, currently litmus jobs in CentOS Stream 9 are still
broken, because the bolt library does not support Ruby >= 3.0, so
these are kept non-voting. We are still waiting for the fix[1], and
will fix the job as soon as the updated version is released.

[1] https://github.com/puppetlabs/bolt/pull/2987

Change-Id: Ibf4d71f6d6d0cf549175df785b8e7a35e65e618f

zuul.d/layout.yaml

@@ -34,7 +34,6 @@
         - puppet-openstack-libraries-puppet-unit-7.10-ubuntu-focal
         - puppet-openstack-libraries-puppet-unit-latest-ubuntu-focal
         - puppet-openstack-libraries-litmus-6.21-ubuntu-focal
-        - puppet-openstack-libraries-litmus-7.10-centos-8-stream
         - puppet-openstack-libraries-litmus-7.10-centos-9-stream
         - puppet-openstack-libraries-litmus-7.10-ubuntu-focal
         - puppet-openstack-libraries-litmus-latest-ubuntu-focal
@@ -44,7 +43,7 @@
         - puppet-openstack-libraries-puppet-syntax-6-ubuntu-focal
         - puppet-openstack-libraries-puppet-unit-6.21-ubuntu-focal
         - puppet-openstack-libraries-puppet-unit-7.10-centos-9-stream
-        - puppet-openstack-libraries-litmus-7.10-centos-8-stream
+        - puppet-openstack-libraries-litmus-7.10-centos-9-stream
 
 # integration jobs
 - project-template:

zuul.d/litmus.yaml

@@ -38,18 +38,11 @@
     abstract: true
     run: playbooks/run-libraries-litmus-tests.yaml
 
-- job:
-    name: puppet-openstack-litmus-7.10-centos-8-stream
-    parent: puppet-openstack-litmus-module-base
-    nodeset: centos-8-stream
-    vars:
-      puppet_gem_version: 7.10.0
-      ceph: pacific
-
 - job:
     name: puppet-openstack-litmus-7.10-centos-9-stream
     parent: puppet-openstack-litmus-module-base
     nodeset: centos-9-stream
+    # TODO(tkajinam): Make job voting once bolt supports Ruby >= 3.0
     voting: false
     vars:
       puppet_gem_version: 7.10.0
@@ -82,17 +75,11 @@
       puppet_gem_version: latest
       ceph: pacific
 
-- job:
-    name: puppet-openstack-libraries-litmus-7.10-centos-8-stream
-    parent: puppet-openstack-litmus-libraries-base
-    nodeset: centos-8-stream
-    vars:
-      puppet_gem_version: 7.10.0
-
 - job:
     name: puppet-openstack-libraries-litmus-7.10-centos-9-stream
     parent: puppet-openstack-litmus-libraries-base
     nodeset: centos-9-stream
+    # TODO(tkajinam): Make job voting once bolt supports Ruby >= 3.0
     voting: false
     vars:
       puppet_gem_version: 7.10.0
@@ -126,10 +113,9 @@
     check:
       jobs:
         - puppet-openstack-litmus-6.21-ubuntu-focal
-        - puppet-openstack-litmus-7.10-centos-8-stream
         - puppet-openstack-litmus-7.10-centos-9-stream
         - puppet-openstack-litmus-7.10-ubuntu-focal
         - puppet-openstack-litmus-latest-ubuntu-focal
     gate:
       jobs:
-        - puppet-openstack-litmus-7.10-centos-8-stream
+        - puppet-openstack-litmus-7.10-centos-9-stream