Fix quic::GetPacketHeaderSize when QuicVersionHasLongHeaderLengths is false

gfe-relnote: Bugfix in quic::GetPacketHeaderSize protected by gfe2_reloadable_flag_quic_fix_get_packet_header_size
PiperOrigin-RevId: 256043642
Change-Id: I1f943400e15a684b5cb84f2a11cbb294859f669e
diff --git a/quic/core/quic_connection_test.cc b/quic/core/quic_connection_test.cc
index 749b3b6..3c5daa9 100644
--- a/quic/core/quic_connection_test.cc
+++ b/quic/core/quic_connection_test.cc
@@ -1141,8 +1141,10 @@
     if (level == ENCRYPTION_INITIAL &&
         peer_framer_.version().KnowsWhichDecrypterToUse()) {
       header.version_flag = true;
-      header.retry_token_length_length = VARIABLE_LENGTH_INTEGER_LENGTH_1;
-      header.length_length = VARIABLE_LENGTH_INTEGER_LENGTH_2;
+      if (QuicVersionHasLongHeaderLengths(peer_framer_.transport_version())) {
+        header.retry_token_length_length = VARIABLE_LENGTH_INTEGER_LENGTH_1;
+        header.length_length = VARIABLE_LENGTH_INTEGER_LENGTH_2;
+      }
     }
     if ((GetQuicRestartFlag(quic_do_not_override_connection_id) ||
          (level == ENCRYPTION_INITIAL &&