Add setting/experiment for small battery devices to have

all forced app standby enabled except for when the device
is charging.

Bug: 69259147
Test: Manual test
Test: atest frameworks/base/services/tests/servicestests/src/com/android/server/ForceAppStandbyTrackerTest.java
Change-Id: Ica3fe6835958f186269413519ee82bc19fb83275