@Override
                           public void onCompleted() {
                               concurrentStreamObserverNumber.addAndGet(-1);
                           }
Create a gRPC stream observer to sending stream data, one stream observer could send multiple stream data by a
single consume. The max number of concurrency allowed at the same time is 10.

@return stream observer
oap-server/server-core/src/main/java/org/apache/skywalking/oap/server/core/remote/client/GRPCRemoteClient.java