Refactor BubbleFlickerHelper to an object

... to align kotlin bset practice.

Also do following refactorings:
1. Remove #setUpBeforeTransition - it's reduandant to setUpRule.
2. Move recordTraceWithTransition to RecordTraceWithTransitionRule
     - it's the only caller.

No logic changes.

Test: atest WMShellExplicitFlickerTestsBubbles
Bug: 396020056
Flag: TEST_ONLY
Change-Id: I26ba38426104492dd997fec5c5b21c1258bf135e