Initialize packet in QuicConnectionTest.

Quiets an msan error. In theory, an uninitialized packet could be successfully decrypted, although that is unlikely.

PiperOrigin-RevId: 896662109

quiche/quic/core/quic_connection_test.cc

diff --git a/quiche/quic/core/quic_connection_test.cc b/quiche/quic/core/quic_connection_test.cc
index 949d7e9..9281193 100644
--- a/quiche/quic/core/quic_connection_test.cc
+++ b/quiche/quic/core/quic_connection_test.cc
@@ -18556,6 +18556,7 @@
   // New packet before OnDecrypedPacket invalidates SCONE. A garbage packet is
   // sufficient.
   char buffer[800];
+  memset(buffer, 0, sizeof(buffer));
   QuicReceivedPacket packet(buffer, sizeof(buffer), QuicTime::Zero());
   ProcessReceivedPacket(kSelfAddress, kPeerAddress, packet);
   EXPECT_CALL(visitor_, OnSconePacket).Times(0);