sys-svc-rdbms: Refactor database service templates and add version support for Magento

- Unified Jinja2 variable spacing in tasks and templates
- Introduced database_image and database_version variables in vars/database.yml
- Updated mariadb.yml.j2 and postgres.yml.j2 to use {{ database_image }}:{{ database_version }}
- Ensured env file paths and includes are consistent
- Prepared support for versioned database images (needed for Magento deployment)

Ref: https://chatgpt.com/share/68b96a9d-c100-800f-856f-cd23d1eda2ed

roles/sys-svc-rdbms/templates/services/mariadb.yml.j2

@@ -5,10 +5,10 @@
     container_name: {{ application_id | get_entity_name }}-database
     logging:
       driver: journald
-    image: mariadb
+    image: {{ database_image }}:{{ database_version }}
     restart: {{ DOCKER_RESTART_POLICY }}
     env_file:
-      - {{database_env}}
+      - {{ database_env }}
     command: "--transaction-isolation=READ-COMMITTED --binlog-format=ROW"
     volumes:
       - database:/var/lib/mysql