Merge "Move unused apps count calculation to bg thread" into sc-dev am: 603cd6c44c am: cbc3c1780d am: cbbb4dbe41

Original change: https://googleplex-android-review.googlesource.com/c/platform/packages/apps/Settings/+/14795269

Change-Id: I4eeb657c2059fe63ac32d6069511e530db599125