message: Set more reasonable size in flow control test
  Summary: There's no reason to make this a huge value to check correctness.
diff: @@ -444,10 +444,9 @@ TEST_P(QuicClientTransportIntegrationTest, FlowControlLimitedTest) {
  eventbase_.loopForever();
  auto streamId = client->createBidirectionalStream().value();
  - client->setStreamFlowControlWindow(streamId, 1024);
  - // TODO: change this once we negotiate the flow control window.
  - auto data = IOBuf::create(kDefaultStreamWindowSize * 4);
  - data->append(kDefaultStreamWindowSize * 4);
  + client->setStreamFlowControlWindow(streamId, 256);
  + auto data = IOBuf::create(4096);
  + data->append(4096);
  memset(data->writableData(), 'a', data->length());
  auto expected = std::shared_ptr<IOBuf>(IOBuf::copyBuffer("echo "));
  