Refactor REST API for Client and Operator Coordinator Communication to Use operatorUid.

Currently, the REST API between clients and operator coordinators relies on the operator ID to send requests to the Job Manager (JM) for querying results. However, with the introduction of Stream Graph submission, the Job Graph will be compiled and generated within the JM, preventing the client from accessing the operator ID.

To address this issue, we modify the REST API for communication between clients and operator coordinators by removing the dependency on operatorID and transitioning to a client-defined String operatorUid.