CI: Detail job removal permission

During the PTG, we discussed one of the challenges was keeping up on
removal of jobs *and* openly giving ourselves permission to remove
jobs which are *not* required after a certian point in time.

The critical aspect to this noting when/what we can clean up without
risk so we don't feel the need to keep things going forever when
there is not as much value to the overall health of the project.

Change-Id: I64f8f09c087d94376cbc32ef678a5da6595a805a

doc/source/contributor/releasing.rst

@@ -338,6 +338,8 @@ This includes:
 
 * In the new stable branch:
 
+  .. NOTE:: OpenStack Release tooling does this automatically.
+
   * a change to point ``.gitreview`` at the branch
   * a change to update the upper constraints file used by ``tox``
 
@@ -349,10 +351,10 @@ This includes:
     typically submit a follow-up patch to do that. An example of this patch is
     `here <https://review.opendev.org/685070>`__.
 
-  * update the `templates` in `.zuul.yaml` or `zuul.d/project.yaml`.
+  * update the ``templates`` in ``.zuul.yaml`` or ``zuul.d/project.yaml``.
 
     The update is necessary to use the job for the next release
-    `openstack-python3-<next_release>-jobs`. An example of this patch is
+    ``openstack-python3-<next_release>-jobs``. An example of this patch is
     `here <https://review.opendev.org/#/c/689705/>`__.
 
 We need to submit patches for changes in the stable branch to:
@@ -364,6 +366,14 @@ We need to submit patches for changes in the stable branch to:
   ``TEMPEST_BAREMETAL_MAX_MICROVERSION`` in ``devstack/lib/ironic`` to make sure
   that unsupported API tempest tests are skipped on stable branches. E.g.
   `patch 495319 <https://review.opendev.org/495319>`_.
+* remove any CI jobs which are *not* required. Mainly this revolves around the
+  metal3-integration CI job, however other non-voting jobs can also be removed
+  safely. This can be achieved by editing the ``.zuul.d/project.yaml`` file.
+
+.. NOTE:: It is normal to reduce the number of CI jobs present on a stable
+   branch the longer the branch exists. This is a mix of challenges related
+   to distributions, dependencies, and CI resources. Maintainers should
+   anticipate this as a normal activity and should avoid heroic efforts.
 
 We need to submit patches for changes on master to:
 

zuul.d/project.yaml

@@ -17,11 +17,6 @@
         - ironic-cross-sushy:
             voting: false
         - ironic-tempest-functional-python3
-        # NOTE(rpittau) moving to non-voting until we fix the tests
-        # see also https://review.opendev.org/c/openstack/ironic-tempest-plugin/+/882312
-        - ironic-grenade
-        - ironic-grenade-skip-level:
-            voting: false
         - ironic-standalone-redfish:
             voting: false
         - ironic-tempest-bios-redfish-pxe
@@ -45,6 +40,16 @@
         # NOTE(rpittau): Currently broken because of an issue with parted
         - metalsmith-integration-glance-centos9-legacy:
             voting: false
+        #####################################################################
+        # Grenade should be removed in advance of the unmaintained branches #
+        # as it doesn't know how to upgrade from an unmaintained branch.    #
+        #####################################################################
+        - ironic-grenade
+        - ironic-grenade-skip-level:
+            voting: false
+        ###############################################################
+        # CI Jobs Below this line may be *removed* on Stable Branches #
+        ###############################################################
         # NOTE(TheJulia): At present, metal3 doesn't leverage
         # stable branches, and as far as we are aware these jobs
         # can be removed once this branch is made stable.