Remove match-any sink in RtpDemuxer::RemoveSink()

RemoveSink() removes a sink from all criteria maps but not from
match_any_sink_. A sink registered with RtpDemuxerCriteria::MatchAny()
therefore stays registered: RemoveSink() returns false, IsEmpty() stays
false, later AddSink() calls are rejected as conflicting, and packets
are still routed to the removed sink.

The only current user, DatagramConnectionInternal, unregisters its
match-any sink in Terminate(). Today that fails and logs an error, but
is otherwise harmless because the connection ignores packets after
termination.

Clear match_any_sink_ in RemoveSink() as well, consistent with
RemoveAllSinks().

Bug: none
Change-Id: I9d927a1daa86fce902920727829dcfc0d7d01278
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/507021
Reviewed-by: Fredrik Solenberg <solenberg@webrtc.org>
Commit-Queue: Tomas Gunnarsson <tommi@webrtc.org>
Auto-Submit: Tomas Gunnarsson <tommi@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#48783}