[automerge] [DO NOT MERGE] Refactor tests to use best practices for ActivityScenario 2p: f2b99a92d3

Original change: https://googleplex-android-review.googlesource.com/c/platform/packages/apps/Car/libs/+/16742226

Change-Id: Idbb78e20fcb2ea4492b5381f589559ac0ecb25a7