This CL adds functionality to remove packets matching a given SSRC from the pacer queue, and calls that with any SSRCs used by an RTP module when that module is removed. Bug: chromium:1395081 Change-Id: I13c0285ddca600e784ad04a806727a508ede6dcc Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/287124 Reviewed-by: Jakob Ivarsson <jakobi@webrtc.org> Commit-Queue: Erik Språng <sprang@webrtc.org> Reviewed-by: Ilya Nikolaevskiy <ilnik@webrtc.org> Reviewed-by: Philip Eliasson <philipel@webrtc.org> Cr-Commit-Position: refs/heads/main@{#38880}