Drop tripleo-ci-centos-9 jobs

tripleo-ci-centos-9-content-provider has been failing for some
time and the other tripleo-ci-centos-9 jobs depend on it.
Based on the recent builds of the jobs outside of
python-tempestconf project it seems they aren't executed on master
anymore.
Due to boh of those reasons this commit drops those jobs.

Change-Id: Ibc7e3a0dd6b661d9c615e087921cc9dd426382a9

.zuul.yaml

@@ -25,39 +25,6 @@
               - ^doc/.*$
               - ^releasenotes/.*$
               - ^.*\.rst$
-        - tripleo-ci-centos-9-content-provider:
-            irrelevant-files: *irrelevant-files
-            voting: false
-        - tripleo-ci-centos-9-scenario002-standalone:
-            irrelevant-files: *irrelevant-files
-            vars: &standalone
-              consumer_job: true
-              build_container_images: false
-              tags:
-                - standalone
-            dependencies:
-              - tripleo-ci-centos-9-content-provider
-        # The job has been constantly failing recently, commenting it out
-        # to unblock the CI. Not marking it n-v as the job takes too long
-        # and as we have a backlog of patches and we know that it's gonna
-        # fail, I have rather commented it out.
-        # https://bugs.launchpad.net/tripleo/+bug/2006649
-        #- tripleo-ci-centos-9-standalone:
-        #    irrelevant-files: *irrelevant-files
-        #    vars: *standalone
-        #    dependencies:
-        #      - tripleo-ci-centos-9-content-provider
-        - tripleo-ci-centos-9-scenario010-standalone:
-            irrelevant-files: *irrelevant-files
-            voting: false
-            vars:
-              consumer_job: true
-              build_container_images: false
-              tags:
-                - standalone
-                - octavia
-            dependencies:
-              - tripleo-ci-centos-9-content-provider
         - opendev-tox-docs
     gate:
       jobs:
@@ -70,19 +37,6 @@
         - python-tempestconf-tempest-devstack-admin-plugins
         - refstack-client-devstack-master:
             irrelevant-files: *irrelevant-files
-        # - tripleo-ci-centos-9-content-provider:
-        #    irrelevant-files: *irrelevant-files
-        - tripleo-ci-centos-9-scenario002-standalone:
-            irrelevant-files: *irrelevant-files
-            vars: *standalone
-            dependencies:
-              - tripleo-ci-centos-9-content-provider
-        # https://bugs.launchpad.net/tripleo/+bug/2006649
-        #- tripleo-ci-centos-9-standalone:
-        #    irrelevant-files: *irrelevant-files
-        #    vars: *standalone
-        #    dependencies:
-        #      - tripleo-ci-centos-9-content-provider
         - opendev-tox-docs
     promote:
       jobs: