Change mariadb image to mariadb-server

Since change [1] merged we have two mariadb images (mariadb and mariadb-server)
Let's use mariadb-server in kolla-ansible, so we can deprecate mariadb image.

[1]: https://review.opendev.org/#/c/710217/

Change-Id: I4ae2ccaaba8fb516f469f4ce8628e8c61de03f0d

ansible/roles/mariadb/defaults/main.yml

@@ -64,7 +64,7 @@ external_haproxy_members: "{% for host in groups['mariadb'] %}server {{ host }}
 # Docker
 ####################
 mariadb_install_type: "{{ kolla_install_type }}"
-mariadb_image: "{{ docker_registry ~ '/' if docker_registry else '' }}{{ docker_namespace }}/{{ kolla_base_distro }}-{{ mariadb_install_type }}-mariadb"
+mariadb_image: "{{ docker_registry ~ '/' if docker_registry else '' }}{{ docker_namespace }}/{{ kolla_base_distro }}-{{ mariadb_install_type }}-mariadb-server"
 mariadb_tag: "{{ openstack_tag }}"
 mariadb_image_full: "{{ mariadb_image }}:{{ mariadb_tag }}"
 

releasenotes/notes/mariadb-server-image-be5f77966586ef39.yaml

+---
+upgrade:
+  - |
+    ``mariadb`` role uses now mariadb-server image by default (compared to
+    ``mariadb`` previously), since ``mariadb`` image will be deprecated in
+    the Kolla Victoria release and removed in Wallaby.