Use a fixed filename for mariadb repository source list

By default, ansible adds a source list file name based on the repository
source url. Using a fixed file name permits to change mirror without
duplicating source list files.

See: https://docs.ansible.com/ansible/latest/modules/apt_repository_module.html

tasks/setup.yml

@@ -16,6 +16,7 @@
 - name: Setup mariadb repository sourcelist entry
   apt_repository:
     repo: deb {{ mariadb_use_official_repo_url }}/{{ mariadb_use_official_repo_version }}/debian {{ ansible_distribution_release }} main
+    filename: mariadb
     state: present
   when: mariadb_use_official_repo