Change a DCHECK in QuicConnection::OnRetransmissionTimeout from `QUICHE_DCHECK(!IsHandshakeComplete())` to `QUICHE_DCHECK(!IsHandshakeConfirmed())`.

At client, if 1) the handshake state is HANDSHAKE_COMPLETE, and 2) there's no inflight packets, then `QuicSentPacketManager::GetRetransmissionTime` may schedule the retransmission alarm, but when the alarm fires, the DCHECK being changed will Check-fail.

PiperOrigin-RevId: 548258788
diff --git a/quiche/quic/core/quic_connection.cc b/quiche/quic/core/quic_connection.cc
index e95c8d1..0ec593b 100644
--- a/quiche/quic/core/quic_connection.cc
+++ b/quiche/quic/core/quic_connection.cc
@@ -4085,7 +4085,7 @@
 #ifndef NDEBUG
   if (sent_packet_manager_.unacked_packets().empty()) {
     QUICHE_DCHECK(sent_packet_manager_.handshake_mode_disabled());
-    QUICHE_DCHECK(!IsHandshakeComplete());
+    QUICHE_DCHECK(!IsHandshakeConfirmed());
   }
 #endif
   if (!connected_) {