Preparation CL to remove RTPTypeHeader. Follow up to this CL (https://webrtc-review.googlesource.com/c/src/+/84423). Bug: none Change-Id: I40516c1791c1ead45e082f554f2f5fcda529e7d6 Reviewed-on: https://webrtc-review.googlesource.com/84588 Reviewed-by: Stefan Holmer <stefan@webrtc.org> Commit-Queue: Philip Eliasson <philipel@webrtc.org> Cr-Commit-Position: refs/heads/master@{#23698}