New code path does not initialize subscribe_id.

Not in production.

PiperOrigin-RevId: 614034075

quiche/quic/moqt/moqt_session.cc

diff --git a/quiche/quic/moqt/moqt_session.cc b/quiche/quic/moqt/moqt_session.cc
index 994c530..a8ee431 100644
--- a/quiche/quic/moqt/moqt_session.cc
+++ b/quiche/quic/moqt/moqt_session.cc
@@ -355,6 +355,7 @@
   write_options.set_send_fin(end_of_stream);
   for (auto subscription : subscriptions) {
     if (forwarding_preference == MoqtForwardingPreference::kDatagram) {
+      object.subscribe_id = subscription->subscribe_id();
       quiche::QuicheBuffer datagram =
           framer_.SerializeObjectDatagram(object, payload);
       // TODO(martinduke): It's OK to just silently fail, but better to notify