Update Docker volumes in docker-compose.yml and enhance Jenkinsfile for frontend testing

- Changed PostgreSQL data volume paths in docker-compose.yml to remove the trailing 'data' directory.
- Improved the 'Test frontend' stage in Jenkinsfile by adding cleanup steps and ensuring the workspace is correctly copied to the Docker container for testing.

docker-compose.yml

@@ -11,7 +11,7 @@ services:
     ports:
       - "5432:5432"
     volumes:
-      - postgres_app_data:/var/lib/postgresql/data
+      - postgres_app_data:/var/lib/postgresql
       - ./scripts/postgres-app-entrypoint.sh:/docker-entrypoint-initdb.d/init-app.sh:ro
     networks:
       - backend-net
@@ -47,7 +47,7 @@ services:
     ports:
       - "5433:5432"
     volumes:
-      - postgres_keycloak_data:/var/lib/postgresql/data
+      - postgres_keycloak_data:/var/lib/postgresql
       - ./scripts/postgres-keycloak-entrypoint.sh:/docker-entrypoint-initdb.d/init-keycloak.sh:ro
     networks:
       - auth-net