Splits PeerConnectionTest.java into 4 files: - PeerConnectionEndToEndTest.java - PeerConnectionTest.java - RtpTranceiverTest.java - VideoTrackTest.java Also deletes some dead code. Bug: None Change-Id: I9b81fec042bc6be261e3010ec5a30baf6d7211bf Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/161680 Reviewed-by: Paulina Hensman <phensman@webrtc.org> Commit-Queue: Sami Kalliomäki <sakal@webrtc.org> Cr-Commit-Position: refs/heads/master@{#30056}