The new TaskQueuePacedSender has been default-on in code since M97, and there are no further usages of it that I can find. Let's clean this up! The PacingController and associated tests will be cleaned up in a follow-up cl. Bug: webrtc:10809 Change-Id: I0cb888602939add953415977ee79ff0b3878fea5 Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/258025 Reviewed-by: Per Kjellander <perkj@webrtc.org> Commit-Queue: Erik Språng <sprang@webrtc.org> Cr-Commit-Position: refs/heads/main@{#36890}