Not assuming that all accessibility events contain bundle

Bundles come from Launcher being explicitly asked a question.
When waiting for ANY event, it may contain any parcelable, so it's
incorrect to cast it to Bundle.

See this:
https://sponge.corp.google.com/target?show=FAILED&sortBy=STATUS&id=9b8d0d26-f81d-427f-8857-b8d71e012504&target=android.test.appsmoke

Bug: 110103162
Test: will watch for reducing flakes in platform tests.
Change-Id: I989cee018183140d7fd672c0a925f03441ca339c