Deprecate quic_allow_variable_length_connection_id_for_negotiation

gfe-relnote: deprecate --gfe2_restart_flag_quic_allow_variable_length_connection_id_for_negotiation
PiperOrigin-RevId: 253919693
Change-Id: Id01ee824886e1777889b1fcc44cd77c0b1e0788a

quic/core/http/end_to_end_test.cc

diff --git a/quic/core/http/end_to_end_test.cc b/quic/core/http/end_to_end_test.cc
index b3aaf20..18e0f2b 100644
--- a/quic/core/http/end_to_end_test.cc
+++ b/quic/core/http/end_to_end_test.cc
@@ -682,11 +682,6 @@
 }
 
 TEST_P(EndToEndTest, ForcedVersionNegotiationAndBadConnectionIdLength) {
-  if (!GetQuicRestartFlag(
-          quic_allow_variable_length_connection_id_for_negotiation)) {
-    ASSERT_TRUE(Initialize());
-    return;
-  }
   if (!QuicUtils::VariableLengthConnectionIdAllowedForVersion(
           GetParam().negotiated_version.transport_version)) {
     ASSERT_TRUE(Initialize());

quic/core/quic_dispatcher_test.cc

diff --git a/quic/core/quic_dispatcher_test.cc b/quic/core/quic_dispatcher_test.cc
index 094b293..43c34f0 100644
--- a/quic/core/quic_dispatcher_test.cc
+++ b/quic/core/quic_dispatcher_test.cc
@@ -548,8 +548,6 @@
 
 TEST_F(QuicDispatcherTest, StatelessVersionNegotiationWithClientConnectionId) {
   SetQuicRestartFlag(quic_do_not_override_connection_id, true);
-  SetQuicRestartFlag(quic_allow_variable_length_connection_id_for_negotiation,
-                     true);
   CreateTimeWaitListManager();
   QuicSocketAddress client_address(QuicIpAddress::Loopback4(), 1);
 

quic/core/quic_utils.cc

diff --git a/quic/core/quic_utils.cc b/quic/core/quic_utils.cc
index 88ffa38..40c50af 100644
--- a/quic/core/quic_utils.cc
+++ b/quic/core/quic_utils.cc
@@ -525,12 +525,6 @@
 // static
 bool QuicUtils::VariableLengthConnectionIdAllowedForVersion(
     QuicTransportVersion version) {
-  if (!GetQuicRestartFlag(
-          quic_allow_variable_length_connection_id_for_negotiation)) {
-    return version >= QUIC_VERSION_47;
-  }
-  QUIC_RESTART_FLAG_COUNT(
-      quic_allow_variable_length_connection_id_for_negotiation);
   // We allow variable length connection IDs for unsupported versions to
   // ensure that IETF version negotiation works when other implementations
   // trigger version negotiation with custom connection ID lengths.

quic/core/quic_versions.cc

diff --git a/quic/core/quic_versions.cc b/quic/core/quic_versions.cc
index 8d7e1c9..cfdacca 100644
--- a/quic/core/quic_versions.cc
+++ b/quic/core/quic_versions.cc
@@ -439,8 +439,6 @@
   SetQuicReloadableFlag(quic_tolerate_reneging, true);
   SetQuicReloadableFlag(quic_simplify_stop_waiting, true);
   SetQuicRestartFlag(quic_no_server_conn_ver_negotiation2, true);
-  SetQuicRestartFlag(quic_allow_variable_length_connection_id_for_negotiation,
-                     true);
   SetQuicRestartFlag(quic_do_not_override_connection_id, true);
   SetQuicRestartFlag(quic_no_framer_object_in_dispatcher, true);
   SetQuicRestartFlag(quic_use_allocated_connection_ids, true);