message: access log: fix integration test flake
diff: @@ -145,6 +145,7 @@ http_logs:
  envoy::api::v2::filter::accesslog::StreamAccessLogsResponse response_msg;
  access_log_request_->sendGrpcMessage(response_msg);
  access_log_request_->finishGrpcStream(Grpc::Status::Ok);
  + test_server_->waitForGaugeEq("cluster.accesslog.upstream_rq_active", 0);
  response = IntegrationUtil::makeSingleRequest(lookupPort("http"), "GET", "/notfound", "",
  downstream_protocol_, version_);
  