Clean up gateway service envs for federated service

[kotharironak]

• gateway service is part of federated service which internally talks to attribute, entity, and query service. And, as they are also bundled as part of federated, we don't need to explicitly exposed HOST and PORT configs for these services to gateway service.
• with this change, we will not need configure gateway service with inherent configs for gateway service

  - ENTITY_SERVICE_HOST_CONFIG=localhost
  - ENTITY_SERVICE_PORT_CONFIG=9001
  - ATTRIBUTE_SERVICE_HOST_CONFIG=localhost
  - ATTRIBUTE_SERVICE_PORT_CONFIG=9001
  - QUERY_SERVICE_HOST_CONFIG=localhost
  - QUERY_SERVICE_PORT_CONFIG=9001

Note: verified locally running entire stack

[kotharironak]

@laxmanchekka I verified this locally with full docker-compose stack, both by overriding property w/o cluster_name property.