message: Pad Initial closes from the client.
  Summary: Otherwise the server can just discard them.
diff: @@ -984,7 +984,7 @@ void writeCloseCommon(
  PacketNum packetNum = header.getPacketSequenceNum();
  // TODO: This too needs to be switchable between regular and inplace builder.
  RegularQuicPacketBuilder packetBuilder(
  - connection.udpSendPacketLen,
  + kDefaultUDPSendPacketLen,
  std::move(header),
  getAckState(connection, pnSpace).largestAckedByPeer.value_or(0));
  packetBuilder.encodePacketHeader();
  @@ -1024,6 +1024,12 @@ void writeCloseCommon(
  break;
  }
  }
  + if (pnSpace == PacketNumberSpace::Initial &&
  + connection.nodeType == QuicNodeType::Client) {
  + while (packetBuilder.remainingSpaceInPkt() > 0) {
  + writeFrame(PaddingFrame(), packetBuilder);
  + }
  + }
  if (written == 0) {
  LOG(ERROR) << "Close frame too large " << connection;
  return;
  