Update NotificationManagerTest to work with FLAG_BUBBLE in BubbleExtractor

Since the flag happens after ranking now we need to add some extra
wait time to the bubbles tests & check the listener instead of polling
active notifs.

Creates a specific bubble check method so that not all of the notification
checks have the extra wait time.

Fixes some things in the tests
- One of them performed checkNotificationExists but didn't actually do
  anything with the value
- The failure messages didn't always make sense so cleaned that up a lil

Test: this is the test
Bug: 149736441
Change-Id: Ic33ace405916420c8437ea58f467c397d9cee2f9
Merged-In: Ic33ace405916420c8437ea58f467c397d9cee2f9