Automotive: Two audio streams playing when starting a new episode without pausing the previous playback

Reported in [5247758-zen](https://woothemes.zendesk.com/agent/tickets/5247758) on:

Car: 2022 Volvo XC60
Android Automotive version 2.1

Issue: two audio streams playing when they tried to listen to a new podcast (while the old one resumed playing automatically when they starts the car)

Video recording:

https://user-images.githubusercontent.com/40906847/170907720-9fcb992c-48d6-46a6-89b7-effa7024c70a.mp4

Start by reproducing the report on Android Automotive using the described Volvo XC60 scenario: resume existing playback when starting the car, then start a new episode. Trace the playback entry points involved in both actions and verify that only the newly selected episode remains audible; done means two audio streams can no longer play simultaneously.

Written by the indexing model from the issue text.