`TransportFeedbackAdapter` return NULL indicates outstanding data is
unchanged. This CL excludes outgoing retransmitted packets, rtcp packets
and invalid transport feedbacks to wakeup pacer.
Bug: webrtc:13417
Change-Id: Ie94956232c13cd548bb7038b5ce76617756fb207
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/238741
Reviewed-by: Henrik Boström <hbos@webrtc.org>
Reviewed-by: Erik Språng <sprang@webrtc.org>
Commit-Queue: Erik Språng <sprang@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#35485}