Skip setting empty status on RMW empty result

Author: alexoneill

test-proxy/src/main/java/com/google/cloud/bigtable/testproxy/CbtTestProxy.java

@@ -691,9 +691,6 @@ public void readModifyWriteRow(
         logger.info(
             String.format(
                 "readModifyWriteRow() did not find row: %s", request.getRequest().getRowKey()));
-        responseObserver.onNext(
-            // Note that the default instance == OK
-            RowResult.newBuilder().setStatus(com.google.rpc.Status.getDefaultInstance()).build());
       }
     } catch (ApiException e) {
       responseObserver.onNext(