Add check to enforce that IETF QUIC client (1) discards packet with an unknown server address and (2) does not start reverse path validation.

PiperOrigin-RevId: 363038408
Change-Id: I7caec059dabe33a2261ed4dd180ffd36ad5b11f5
diff --git a/quic/test_tools/quic_test_client.cc b/quic/test_tools/quic_test_client.cc
index 8480b04..8c58cd7 100644
--- a/quic/test_tools/quic_test_client.cc
+++ b/quic/test_tools/quic_test_client.cc
@@ -311,6 +311,9 @@
 
 void MockableQuicClient::set_peer_address(const QuicSocketAddress& address) {
   mockable_network_helper()->set_peer_address(address);
+  if (client_session() != nullptr) {
+    client_session()->AddKnownServerAddress(address);
+  }
 }
 
 const QuicReceivedPacket* MockableQuicClient::last_incoming_packet() {