gfe-relnote: (n/a) Always handle MSG_TOO_BIG when sending buffered packets. Protected by existing --gfe2_reloadable_flag_quic_treat_queued_packets_as_sent.

Currently this code is protected by both 'treat_queued_packets_as_sent' and 'mtu_discovery_v2', removing the latter is fine because the former will not be verified until the week after the next.

PiperOrigin-RevId: 275084849
Change-Id: Id460685b2beef5bb77c8a3d98047e4725f249ed7

quic/core/quic_connection.cc

diff --git a/quic/core/quic_connection.cc b/quic/core/quic_connection.cc
index 545d46b..0b4c05f 100644
--- a/quic/core/quic_connection.cc
+++ b/quic/core/quic_connection.cc
@@ -2054,7 +2054,7 @@
         packet.encrypted_buffer.data(), packet.encrypted_buffer.length(),
         packet.self_address.host(), packet.peer_address, per_packet_options_);
     QUIC_DVLOG(1) << ENDPOINT << "Sending buffered packet, result: " << result;
-    if (mtu_discovery_v2_ && IsMsgTooBig(result) &&
+    if (IsMsgTooBig(result) &&
         packet.encrypted_buffer.length() > long_term_mtu_) {
       // When MSG_TOO_BIG is returned, the system typically knows what the
       // actual MTU is, so there is no need to probe further.