Upgrade Etherpad's MariaDB to 10.11

We are currently running MariaDB 10.4 for etherpad. We use the
MARIADB_AUTO_UPGRADE flag to automatically upgrade the mariadb install
to 10.11 when switching the image version over to 10.11. This was
successfully performed against the lodgeit paste service.

Change-Id: Id7dae260f3611fc1f88858730567455fef782b1c

playbooks/roles/etherpad/templates/docker-compose.yaml.j2

@@ -4,7 +4,7 @@ version: '2'
 
 services:
   mariadb:
-    image: docker.io/library/mariadb:10.4
+    image: docker.io/library/mariadb:10.11
     network_mode: host
     restart: always
     environment:
@@ -12,6 +12,7 @@ services:
       MYSQL_DATABASE: etherpad-lite
       MYSQL_USER: "{{ etherpad_db_user }}"
       MYSQL_PASSWORD: "{{ etherpad_db_password }}"
+      MARIADB_AUTO_UPGRADE: 1
     volumes:
       - /var/etherpad/db:/var/lib/mysql
       - /etc/etherpad/mysql:/etc/mysql/conf.d

testinfra/test_etherpad.py

@@ -34,7 +34,7 @@ def test_etherpad_logs(host):
 
     mariadb_log_file = host.file('/var/log/containers/docker-mariadb.log')
     assert mariadb_log_file.exists
-    assert mariadb_log_file.contains('mysqld: ready for connections')
+    assert mariadb_log_file.contains('mariadbd: ready for connections.')
 
 def test_etherpad_4_byte_utf8(host):
     # The 🖖 utf8 character is a four byte character. This test ensures we