message: tperf: use maxToSend directly for each stream
  Summary: ^
diff: @@ -129,8 +129,7 @@ class ServerStreamHandler : public quic::QuicSocket::ConnectionCallback,
  void onStreamWriteReady(
  quic::StreamId id,
  uint64_t maxToSend) noexcept override {
  - auto buf = folly::IOBuf::createChain(
  - std::max<uint64_t>(maxToSend / numStreams_, 64), blockSize_);
  + auto buf = folly::IOBuf::createChain(maxToSend, blockSize_);
  auto curBuf = buf.get();
  do {
  curBuf->append(curBuf->capacity());
  