Remove function declarations, members, and friend tests that are no longer used. Reorder the member variables. Bug: webrtc:7494 Change-Id: I8c24e2f4b9d9846e6d3fef4e2c998aa26f49f8c9 Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/282180 Reviewed-by: Alessio Bazzica <alessiob@webrtc.org> Commit-Queue: Hanna Silen <silen@webrtc.org> Cr-Commit-Position: refs/heads/main@{#38570}