message: Fix unstable unit test
  Looks like we have to properly shutdown message queue
  in the unit test which emulates data sending over the
  secured websocket session. Otherwise, unit test might
  be terminated earlier and data sending will be failed
  which causes a core crash.
diff: @@ -141,6 +141,10 @@ TEST_F(WebsocketNotSecureSessionConnectionTest, SUCCESS_SendData) {
  auto error = websocket_connection_->SendData(message);
  ASSERT_EQ(TransportAdapter::Error::OK, error);
  +
  + auto disconnect_error = websocket_connection_->Disconnect();
  +
  + ASSERT_EQ(TransportAdapter::Error::OK, disconnect_error);
  }
  TEST_F(WebsocketNotSecureSessionConnectionTest, UNSUCCESS_SendData_BAD_STATE) {
  