[skip ci] Add graceful stop grpc server log in indexcoord (#12922)

Signed-off-by: Nyun.zhang <yun.zhang@zilliz.com>
Co-authored-by: Nyun.zhang <yun.zhang@zilliz.com>

internal/distributed/indexcoord/service.go

@@ -126,6 +126,7 @@ func (s *Server) Stop() error {
 
 	s.loopCancel()
 	if s.grpcServer != nil {
+		log.Debug("Graceful stop grpc server...")
 		s.grpcServer.GracefulStop()
 	}