Update mariadb upload job

A previous change[0] added an ubuntu bionic Dockerfile for mariadb
but did not update the zuul file to properly tag the new image.

This change updates the zuul job in order to correctly tag the image,
as well as simplifying the ability to specify the ubuntu release.

Also updates the previous change's bionic Dockerfile to focal.

[0] https://review.opendev.org/c/openstack/openstack-helm-images/+/782843

Change-Id: I0c803bf1d2d4705b669a48bba0b9576c71d4b77d

mariadb/Dockerfile.ubuntu_focal

@@ -1,10 +1,10 @@
-# mariadb:10.5.3-bionic
-ARG FROM=docker.io/mariadb@sha256:bd5b3470601aa4a28132ec60a8b1c33516d09a1391864fe1dbf82a4030397fd1
+# mariadb:10.5.9-focal
+ARG FROM=docker.io/mariadb@sha256:7e244fae615587335176db07e88b43eee5e4762f35306e17c13c68125d93b9bf
 FROM ${FROM}
 
 RUN set -ex ;\
-    apt-get update ;\
-    apt-get install -y --no-install-recommends \
+    apt update ;\
+    apt install -y --no-install-recommends \
         python3-pip ;\
     pip3 --no-cache-dir install --upgrade pip ;\
     hash -r ;\
@@ -14,7 +14,7 @@ RUN set -ex ;\
       iso8601 \
       kubernetes \
       pykube-ng ;\
-    apt-get clean -y ;\
+    apt clean -y ;\
     rm -rf \
        /var/cache/debconf/* \
        /var/lib/apt/lists/* \

zuul.d/mariadb.yaml

@@ -37,13 +37,14 @@
     description: Build mariadb images
     vars: &mariadb_vars
       currentdate: "{{ now(utc=True,fmt='%Y%m%d') }}"
+      release: "focal"
       docker_images:
         - context: mariadb
           repository: openstackhelm/mariadb
-          dockerfile: Dockerfile.ubuntu_xenial
+          dockerfile: Dockerfile.ubuntu_{{ release }}
           tags:
-            - latest-ubuntu_xenial
-            - "ubuntu_xenial-{{ currentdate }}"
+            - "latest-ubuntu_{{ release }}"
+            - "ubuntu_{{ release }}-{{ currentdate }}"
     files: &mariadb_files
       - mariadb/.*
       - zuul.d/mariadb.yaml