Remove Listener dependency in the telecom test app.

Yes, it kinda breaks the conference stuff, but I need to revamp that in
another CL for another purpose sometime soon, so this is okay for now.

Bug: 141576016
Test: Manual smoke test.
Test: Run unit tests.
Test: Run CTS tests.
Change-Id: Ie0582eeebb60880a70ddff4145f24f70e038131f