mux api: refine previous PR (#73)

Use the existing RateLimited message.

Signed-off-by: Matt Klein <mklein@bitdrift.io>

Author: mattklein123

src/bitdrift_public/protobuf/client/v1/api.proto

@@ -325,9 +325,10 @@ message HandshakeResponse {
   uint32 configuration_update_status = 2;
 }
 
-// A general indication of rate limiting from server to client. Further configuration of what to do
-// when limited can be added later.
+// A general indication of rate limiting from server to client.
 message RateLimited {
+  // Optional minimum retry backoff duration that the client should adhere to.
+  google.protobuf.Duration retry_after = 1;
 }
 
 // A response to an upload request, intended to ack or nack the success of the
@@ -469,8 +470,8 @@ message ErrorShutdown {
   // The message that would have been sent in trailers.
   string grpc_message = 2;
 
-  // Optional minimum retry backoff duration that the client should adhere to.
-  google.protobuf.Duration retry_after = 3;
+  // Optional rate limiting that the client should adhere to.
+  RateLimited rate_limited = 3;
 }
 
 // Called by the server to tell the client to flush a set of owned buffers. When this command is