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/host_vars/dockerbox.yml

@@ -33,7 +33,7 @@ docker_compose_deploy:
   # Nextcloud
   - name: nextcloud
     url: https://github.com/krislamo/nextcloud
-    version: 0abc5cc6ba64ed94b7ddc6fd934f0fd62b8a6d11
+    version: fe6d349749f178e91ae7ff726d557f48ebf84356
     env:
       DATA: ./data