Transition BatteryStatsLoadTests to BatteryUsageStats API

Also, return metrics to the instrumentation instead of just
logging.

Also, clean up handling of the BATTERY_CHANGED broadcast.

Bug: 175324611
Test: mp :BatteryStatsLoadTests && ash am instrument -w -e class com.android.frameworks.core.batterystatsloadtests.SystemServiceCallLoadTest com.android.frameworks.core.batterystatsloadtests/androidx.test.runner.AndroidJUnitRunner
Change-Id: I9bc7ad361fb31fa7d53a7e383c09b1f1770db530
4 files changed