[CI] Use images from quay.io

Based on the discussions from the past 3 Kolla meetings [1][2][3],
we established that, to avoid the DockerHub pull limit issues
in our CI, we will try using quay.io.

The images have already been published via Kolla CI
for master/Wallaby [4] and Victoria [5].

This change applies only to CI.
The user-facing move is yet to be discussed.

[1] http://eavesdrop.openstack.org/meetings/kolla/2021/kolla.2021-03-17-15.00.log.html#l-102
[2] http://eavesdrop.openstack.org/meetings/kolla/2021/kolla.2021-03-24-15.00.log.html#l-137
[3] http://eavesdrop.openstack.org/meetings/kolla/2021/kolla.2021-03-31-15.01.log.html#l-50
[4] https://review.opendev.org/c/openstack/kolla/+/781130
[5] https://review.opendev.org/c/openstack/kolla/+/781899

Change-Id: I22e11a994801447526ac26fc2815a1679876225e
(cherry picked from commit 9c045aee36)

tests/templates/globals-default.j2

@@ -44,8 +44,10 @@ docker_namespace: "lokolla"
 docker_registry: "primary:4000"
 openstack_tag: "{{ build_image_tag }}"
 {% else %}
-# use docker hub images
-docker_namespace: "kolla"
+# use the published images from a site mirror of quay.io
+docker_registry: "{{ zuul_site_mirror_fqdn }}:4447"
+docker_registry_insecure: no
+docker_namespace: openstack.kolla
 {% if docker_image_tag_suffix %}
 openstack_tag_suffix: "{{ docker_image_tag_suffix }}"
 {% endif %}