Upgrade Nextcloud setup to use compose files

- Integrated MariaDB role into Dockerbox configuration
- Moved proxy role to the end to avoid early endpoint activation
- Temporarily disabled select roles for future re-evaluation
- Introduced flush_handlers task for early MariaDB restart
- Moved a few Nextcloud tasks to handlers
- Configured Nextcloud to utilize the host's MariaDB instance
- Enhanced overall code linting quality

dev/dockerbox.yml

@@ -6,8 +6,7 @@
   roles:
     - base
     - docker
+    - mariadb
     - traefik
     - nextcloud
-    - jenkins
-    - prometheus
-    - nginx
+    - proxy