Downgrade QUIC_BUG to DLOG(WARNING) when idle network deadline has passed during liveness testing.

PiperOrigin-RevId: 338533930
Change-Id: Ib2fb7a5bf01d1c46831014c23f9000b701507ebb

quic/core/quic_connection.cc

diff --git a/quic/core/quic_connection.cc b/quic/core/quic_connection.cc
index 5b9ab32..91e3ea0 100644
--- a/quic/core/quic_connection.cc
+++ b/quic/core/quic_connection.cc
@@ -737,7 +737,7 @@
   }
   const QuicTime now = clock_->ApproximateNow();
   if (now > idle_network_deadline) {
-    QUIC_BUG << "Idle network deadline has passed";
+    QUIC_DLOG(WARNING) << "Idle network deadline has passed";
     return false;
   }
   const QuicTime::Delta timeout = idle_network_deadline - now;