svc: Remove use of the VideoFrameTrackingIdAdvertised trial

AV1 tests seem to be running fine now that we have the dependency
descriptor enabled, so remove the need for the RTP header extension
as it doesn't allow discarding frames.

Bug: webrtc:11607
Change-Id: Ifd0670ab61a5b69d0570f65ba30c352a31376992
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/273488
Reviewed-by: Artem Titov <titovartem@webrtc.org>
Auto-Submit: Florent Castelli <orphis@webrtc.org>
Commit-Queue: Florent Castelli <orphis@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#37952}

pc/test/svc_e2e_tests.cc

@@ -244,9 +244,7 @@ MATCHER_P2(HasSpatialAndTemporalLayers,
 }
 
 TEST_P(SvcTest, ScalabilityModeSupported) {
-  // Track frames using an RTP header instead of modifying the encoded data as
-  // this doesn't seem to work for AV1.
-  std::string trials = "WebRTC-VideoFrameTrackingIdAdvertised/Enabled/";
+  std::string trials;
   if (UseDependencyDescriptor()) {
     trials += "WebRTC-DependencyDescriptorAdvertised/Enabled/";
   }