Deprecate RemoveTrack (old signature)

This also removes all internal usage of RemoveTrack, and changes
the replacement function to RemoveTrackOrError rather than RemoveTrackNew.

Bug: webrtc:9534
Change-Id: Idf7bb17495686de77c70428dcbfb12278328ce59
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/244094
Reviewed-by: Niels Moller <nisse@webrtc.org>
Reviewed-by: Henrik Boström <hbos@webrtc.org>
Commit-Queue: Harald Alvestrand <hta@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#35624}
diff --git a/api/test/mock_peerconnectioninterface.h b/api/test/mock_peerconnectioninterface.h
index cd67d32..fc740b0 100644
--- a/api/test/mock_peerconnectioninterface.h
+++ b/api/test/mock_peerconnectioninterface.h
@@ -50,7 +50,7 @@
               (override));
   MOCK_METHOD(bool, RemoveTrack, (RtpSenderInterface*), (override));
   MOCK_METHOD(RTCError,
-              RemoveTrackNew,
+              RemoveTrackOrError,
               (rtc::scoped_refptr<RtpSenderInterface>),
               (override));
   MOCK_METHOD(RTCErrorOr<rtc::scoped_refptr<RtpTransceiverInterface>>,