Revert "zun: Deprecate Zun provisionally"

This reverts commit f8d4db54.

Reason for revert: Zun was deprecated due to the hard dependency on old version of docker and etcd. Right now, the problem was fixed.

Change-Id: I9fe760e2b9b774b5ea623e6b305de004fc0c6dd2

ansible/roles/prechecks/tasks/service_checks.yml

@@ -64,15 +64,6 @@
   when:
     - (enable_ceph | default()) | bool
 
-- name: Validate that enable_zun is disabled
-  run_once: True
-  fail:
-    msg: |
-      Apologies, Zun is currently not supported for this release.
-      Please consult the release notes.
-  when:
-    - (enable_zun | default()) | bool
-
 - name: Validate rabbitmq variables
   run_once: True
   fail:

doc/source/reference/compute/zun-guide.rst

@@ -8,18 +8,6 @@ workload on OpenStack."
 For more details about Zun, see `OpenStack Zun Documentation
 <https://docs.openstack.org/zun/latest/>`__.
 
-.. warning::
-
-   Zun is currently NOT SUPPORTED for this version of Kolla-Ansible.
-
-   Since work on repairing compatibility is expected to start development
-   during the 2024.1 release cycle, backports will be considered to the
-   stable series to bridge the migration path.
-
-   While the service containers and ansible roles still remain, a working
-   installation is currently not possible in CI, and therefore is not
-   supported.
-
 Preparation and Deployment
 --------------------------
 

releasenotes/notes/zun-provisional-deprecation-1db1295f733ec3fe.yaml

----
-upgrade:
-  - |
-    Support for Zun for this release has been provisionally dropped. This is
-    due to a number of base dependencies that require updating. The Zun images
-    remain buildable, and the roles have not been removed, but a precheck
-    has been added to prevent breaking current deployments.
-
-    Operators are strongly encouraged to hold off upgrading if Zun is a
-    requirement. Please also consult the deprecation notes.
-deprecations:
-  - |
-    Zun is currently provisionally deprecated but not removed. If Zun regains
-    compatibility within the next release cycle, backports to this version of
-    Kolla and Kolla-Ansible will be considered to provide a smooth upgrade
-    path.

zuul.d/project.yaml

@@ -25,6 +25,8 @@
         - kolla-ansible-ubuntu-multinode-ipv6
         - kolla-ansible-rocky9-bifrost
         - kolla-ansible-ubuntu-bifrost
+        - kolla-ansible-rocky9-zun
+        - kolla-ansible-ubuntu-zun
         - kolla-ansible-rocky9-swift
         - kolla-ansible-ubuntu-swift
         - kolla-ansible-rocky9-scenario-nfv