Removes a few constructors where similar ones existed. Removes MediaConfig dependency from MediaChannel and fixes an iwyu. Bug: none Change-Id: I9e34a1da0852c3fb21222161fad315e70598db3a Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/242966 Auto-Submit: Tomas Gunnarsson <tommi@webrtc.org> Reviewed-by: Niels Moller <nisse@webrtc.org> Commit-Queue: Niels Moller <nisse@webrtc.org> Cr-Commit-Position: refs/heads/main@{#35608}