/service/rest/v1/status returns 200 status code when node is read-only

http://<hostname>:<port>/service/rest/v1/status currently returns 200 status code if the specific node being accessed is in a read-only state.

The main use case of adding this endpoint was to determine the availability of a node that is in an HA-C cluster.

Given an HA-C node is not fully functional unless it is writable, there needs to be an endpoint that returns 503 service unavailable if:

• the node is read-only
• all other criteria of a valid HA-C node participant are satisfied

By meeting these requirements, a load balancer can more accurately represent if a node is ready to server ALL types of requests.

Note: A side benefit of this endpoint may have been to see if a node is "alive" at all ie. is up, but is read-only. We need to answer what endpoint should be used for this use case - should it be this endpoint or something else?