Fix Transition test logic and consolidate some boilerplate

Moved things to use TransitionInfoBuilder instead of constructing
TransitionInfos directly.

Also make the testapi for ChangeInfo properly populate itself based
on the container. This exposed some incorrectness in the tests, so
fixed those as well

Bug: 261418859
Test: TransitionTests ShellTransitionTests
Change-Id: Ibe1945986ac0342fae0df0f952c727821e4a60a2