message: Remove unused isBidirectionalStream() function to unblock auto-syncer
  Summary: Removing unused isBidirectionalStream() function.
diff: @@ -57,13 +57,6 @@ bool isUnidirectionalStream(quic::StreamId stream) {
  return stream & 0b10;
  }
  -/**
  - * Returns whether the given StreamId identifies a bidirectional stream.
  - */
  -bool isBidirectionalStream(quic::StreamId stream) {
  - return !isUnidirectionalStream(stream);
  -}
  -
  // The octet following the version contains the lengths of the two connection ID
  // fields that follow it
  constexpr size_t kConnIdLengthOctet = 1;
  