Revert "Pin zun jobs to Docker 20"

This reverts commit 94a74f58c7891e41ca637c4e2a6450ca88cbfb56.

Reason for revert: Zun/Kuryr-libnetwork has switched to "local" scope which doesn't require docker 20 anymore. It should work for latest docker version. Related patches:
https://review.opendev.org/c/openstack/zun/+/903884

Change-Id: Ieb545ae5a5917322f599728587c3f04ea8356126

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

@@ -35,20 +35,6 @@ following variables:
    docker_configure_for_zun: "yes"
    containerd_configure_for_zun: "yes"
 
-Currently Kuryr does not support Docker 23 and later due to
-dropped --cluster-store option (bug
-`bug <https://bugs.launchpad.net/zun/+bug/2007142>`__).You need
-to cap docker by setting the following variables in globals.yml.
-
-.. code-block:: yaml
-
-   docker_apt_package_pin: "5:20.*"
-   docker_yum_package_pin: "20.*"
-
-Debian Bookworm is not recommended as a host OS for Zun.
-It does not support a version of Docker with the deprecated option.
-Compatibility with Zun is not tested in CI.
-
 Docker reconfiguration requires rebootstrapping before deploy.
 Make sure you understand the consequences of restarting Docker.
 Please see :ref:`rebootstrapping` for details.

tests/templates/globals-default.j2

@@ -86,9 +86,6 @@ enable_cinder: "yes"
 # lvm backup driver for cinder-backup does not exist
 enable_cinder_backup: "no"
 enable_cinder_backend_lvm: "yes"
-# pin Docker to 20 - https://bugs.launchpad.net/zun/+bug/2007142
-docker_apt_package_pin: "5:20.*"
-docker_yum_package_pin: "20.*"
 {% endif %}
 
 {% if scenario == "swift" %}

zuul.d/base.yaml

@@ -132,7 +132,6 @@
       - ^tests/test-core-openstack.sh
       - ^tests/test-zun.sh
       - ^tests/test-dashboard.sh
-      - ^tests/templates/globals-default\.j2$
     vars:
       scenario: zun