Do not send retry token on non-initial packets

gfe-relnote: fix retry issue, protected by disabled flag quic_enable_v99
PiperOrigin-RevId: 249048340
Change-Id: I51675769cc81358334338e4c6f602a042f36dbbf

quic/core/quic_packet_creator.cc

diff --git a/quic/core/quic_packet_creator.cc b/quic/core/quic_packet_creator.cc
index 77b5971..e69ac85 100644
--- a/quic/core/quic_packet_creator.cc
+++ b/quic/core/quic_packet_creator.cc
@@ -829,7 +829,12 @@
 }
 
 QuicStringPiece QuicPacketCreator::GetRetryToken() const {
-  return retry_token_;
+  if (QuicVersionHasLongHeaderLengths(framer_->transport_version()) &&
+      HasIetfLongHeader() &&
+      EncryptionlevelToLongHeaderType(packet_.encryption_level) == INITIAL) {
+    return retry_token_;
+  }
+  return QuicStringPiece();
 }
 
 void QuicPacketCreator::SetRetryToken(QuicStringPiece retry_token) {