refactor(docker): remove dead code (#8554)

Side quest of #8545. Looks like this file is not being used at all.

docker-compose.maintenance.yml

@@ -1,35 +0,0 @@
-# Todo: !!! This file seems related to our old maintenance worker for MongoDB and has to be refactored in case of using it !!!
-
-services:
-  maintenance-worker:
-    image: ghcr.io/ocelot-social-community/ocelot-social/develop-maintenance-worker:latest
-    build:
-      context: deployment/legacy-migration/maintenance-worker
-    volumes:
-      - uploads:/uploads
-      - neo4j-data:/data
-      - ./deployment/legacy-migration/maintenance-worker/migration/:/migration
-      - ./deployment/legacy-migration/maintenance-worker/ssh/:/root/.ssh
-    environment:
-      - NEO4J_dbms_security_auth__enabled=false
-      - NEO4J_dbms_memory_heap_max__size=2G
-      - GRAPHQL_URI=http://localhost:4000
-      - CLIENT_URI=http://localhost:3000
-      - JWT_SECRET=b/&&7b78BF&fv/Vd
-      - PRIVATE_KEY_PASSPHRASE=a7dsf78sadg87ad87sfagsadg78
-      - NEO4J_apoc_import_file_enabled=true
-      - "SSH_USERNAME=${SSH_USERNAME}"
-      - "SSH_HOST=${SSH_HOST}"
-      - "MONGODB_USERNAME=${MONGODB_USERNAME}"
-      - "MONGODB_PASSWORD=${MONGODB_PASSWORD}"
-      - "MONGODB_AUTH_DB=${MONGODB_AUTH_DB}"
-      - "MONGODB_DATABASE=${MONGODB_DATABASE}"
-      - "UPLOADS_DIRECTORY=${UPLOADS_DIRECTORY}"
-      - "MONGO_EXPORT_SPLIT_SIZE=${MONGO_EXPORT_SPLIT_SIZE}"
-    ports:
-      - 7687:7687
-      - 7474:7474
-
-volumes:
-  neo4j-data:
-  uploads: