@menghanl updated health from the health.proto which had breaking changes(and it is now rolled back) in #2263.

This added a new method named rpc Watch() to service Health (in addition to rpc Check() that already existed).

This is not desirable and breaks all downstreams implementing the grpc.health.v1.Health service (emphasis on v1). v1 is not supposed to break.

This clearly breaks:

• tools like https://github.com/grpc-ecosystem/grpc-health-probe
• grpc servers like https://github.com/GoogleCloudPlatform/microservices-demo/

I will be lobbying internally to not to add this RPC in a breaking way.

In the meanwhile, please revert this change from grpc-go.
cc: @markdroth