Using View.performHapticFeedback on Back Panel Controller when the back gesture is handled

Migration towards the new one-way API that can trigger haptic feedback from the UI thread. Calls to cancel vibrations and vibrations triggered in a separate thread (old API) have been replaced by calls to performHapticFeedback directly from the UI thread. Delaying cancellations and delayed haptics is no longer necessary. The migration is controlled by a feature flag at the moment.

Test: Tests that handled back gesture-committed and -cancelled now verify different method calls from the VibratorHelper depending on the feature flag.
Bug: 245528624
Change-Id: I5e3b8d67f26cd7002d2372f116ec2601053c4328