Add tron counter for battery % too

Bug: 72229630
Test: manual test with dumpsys power, etc
Test:  atest $ANDROID_BUILD_TOP/frameworks/base/services/tests/servicestests/src/com/android/server/power/batterysaver/BatterySavingStatsTest.java
Change-Id: Iec9972a65f8a71bbcc85a1c177b268e91f90c434