[Predictive Back] If back swipe while widget picker is in search mode, we...

[Predictive Back] If back swipe while widget picker is in search mode, we should scale down the content view, rather than the bottom sheet

This will help indicate that we will be navigating within widget picker's bottom sheet.

Fix: 333524244
Test: manual - took a video
Flag: aconfig com.android.launcher3.enable_predictive_back_gesture TEAMFOOD
Change-Id: If29806a474d35c0fdd5789cb67fa62dfbb313313