Deprecate gfe2_reloadable_flag_quic_clear_undecryptable_packets_on_handshake_complete.

PiperOrigin-RevId: 430204927
diff --git a/quic/core/quic_connection.cc b/quic/core/quic_connection.cc
index 77c0609..09fb156 100644
--- a/quic/core/quic_connection.cc
+++ b/quic/core/quic_connection.cc
@@ -4446,15 +4446,7 @@
 
   // Once handshake is complete, there will be no new keys installed and hence
   // any undecryptable packets will never be able to be decrypted.
-  bool clear_undecryptable_packets =
-      encryption_level_ == ENCRYPTION_FORWARD_SECURE;
-  if (GetQuicReloadableFlag(
-          quic_clear_undecryptable_packets_on_handshake_complete)) {
-    QUIC_RELOADABLE_FLAG_COUNT(
-        quic_clear_undecryptable_packets_on_handshake_complete);
-    clear_undecryptable_packets = IsHandshakeComplete();
-  }
-  if (clear_undecryptable_packets) {
+  if (IsHandshakeComplete()) {
     if (debug_visitor_ != nullptr) {
       for (const auto& undecryptable_packet : undecryptable_packets_) {
         debug_visitor_->OnUndecryptablePacket(
diff --git a/quic/core/quic_flags_list.h b/quic/core/quic_flags_list.h
index 7e5183d..5244028 100644
--- a/quic/core/quic_flags_list.h
+++ b/quic/core/quic_flags_list.h
@@ -41,8 +41,6 @@
 QUIC_FLAG(FLAGS_quic_reloadable_flag_quic_allow_client_enabled_bbr_v2, false)
 // If true, change QuicCryptoServerStream::FinishProcessingHandshakeMessageAfterProcessClientHello to noop if connection is disconnected.
 QUIC_FLAG(FLAGS_quic_reloadable_flag_quic_crypto_noop_if_disconnected_after_process_chlo, true)
-// If true, clear undecryptable packets on handshake complete.
-QUIC_FLAG(FLAGS_quic_reloadable_flag_quic_clear_undecryptable_packets_on_handshake_complete, true)
 // If true, close read side but not write side in QuicSpdyStream::OnStreamReset().
 QUIC_FLAG(FLAGS_quic_reloadable_flag_quic_fix_on_stream_reset, true)
 // If true, default on PTO which unifies TLP + RTO loss recovery.