Enable GetRemoteAudioSSLCertificate tests for Unified Plan
Enable GetRemoteAudioSSLCertificate tests for Unified Plan

They were disabled since GetRemoteAudioSSLCertificate was written
in terms of voice/video channel, which were not methods supported
with Unified Plan. Now GetRemoteAudioSSLCertificate has been
rewritten to work with RtpTransceivers, so the test can be enabled.

Bug: webrtc:8764
Change-Id: I08b5fbcc0d69f36113a281c902db6508fa48ebdd
Reviewed-on: https://webrtc-review.googlesource.com/55923
Reviewed-by: Seth Hampson <5a50a6f73a991bd7236b2b9fd2e9f2207db14f62@webrtc.org>
Commit-Queue: Steve Anton <93f73658da16553b94c040887a439a155812e54e@webrtc.org>
Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#22115}
TimothyGu/libilbc,ShiftMediaProject/libilbc,TimothyGu/libilbc,TimothyGu/libilbc,ShiftMediaProject/libilbc,TimothyGu/libilbc,TimothyGu/libilbc,ShiftMediaProject/libilbc,ShiftMediaProject/libilbc,ShiftMediaProject/libilbc