Don't use mock TaskViewTransitions in BubblesTest

I wasn't able to reproduce the test failure but I think this might
be the issue. Tests pass locally with non-mocked TaskViewTransitions.

Test: atest BubblesTest
Bug: 289444898
Bug: 288981689
Change-Id: Iddfb6a2c863083bff6f56713684b1c99b77a46db