Fix MSAN error in MoqtSimulator.

The visitor has to be destroyed after the subscription.

PiperOrigin-RevId: 824587181
diff --git a/quiche/quic/moqt/test_tools/moqt_simulator.cc b/quiche/quic/moqt/test_tools/moqt_simulator.cc
index 4c598d6..b39ba42 100644
--- a/quiche/quic/moqt/test_tools/moqt_simulator.cc
+++ b/quiche/quic/moqt/test_tools/moqt_simulator.cc
@@ -255,6 +255,7 @@
 
 MoqtSimulator::MoqtSimulator(const SimulationParameters& parameters)
     : simulator_(quic::QuicRandom::GetInstance()),
+      receiver_(simulator_.GetClock(), parameters.deadline),
       client_endpoint_(&simulator_, "Client", "Server", kMoqtVersion),
       server_endpoint_(&simulator_, "Server", "Client", kMoqtVersion),
       switch_(&simulator_, "Switch", 8, AdjustedQueueSize(parameters)),
@@ -266,7 +267,6 @@
       generator_(&simulator_, "Client generator", client_endpoint_.session(),
                  TrackName(), parameters.keyframe_interval, parameters.fps,
                  parameters.i_to_p_ratio, parameters.bitrate),
-      receiver_(simulator_.GetClock(), parameters.deadline),
       adjuster_(simulator_.GetClock(), client_endpoint_.session()->session(),
                 &generator_),
       parameters_(parameters) {
diff --git a/quiche/quic/moqt/test_tools/moqt_simulator.h b/quiche/quic/moqt/test_tools/moqt_simulator.h
index a9452da..160a23f 100644
--- a/quiche/quic/moqt/test_tools/moqt_simulator.h
+++ b/quiche/quic/moqt/test_tools/moqt_simulator.h
@@ -221,6 +221,7 @@
 
  private:
   quic::simulator::Simulator simulator_;
+  ObjectReceiver receiver_;
   MoqtClientEndpoint client_endpoint_;
   MoqtServerEndpoint server_endpoint_;
   quic::simulator::Switch switch_;
@@ -229,7 +230,6 @@
   quic::simulator::SymmetricLink server_link_;
   MoqtKnownTrackPublisher publisher_;
   ObjectGenerator generator_;
-  ObjectReceiver receiver_;
   MoqtBitrateAdjuster adjuster_;
   SimulationParameters parameters_;