Merge "Improve wallpaper preview loading transition" into sc-dev am: de34ad568d am: fe1c5c9bb8

Original change: https://googleplex-android-review.googlesource.com/c/platform/packages/apps/WallpaperPicker2/+/14970016

Change-Id: I31df39021daaaca66ee7b72e11d600630dba63ea