Clean up obsolete battery settings files

Fixes: 112440820
Test: robotest still pass
Change-Id: I91e8a4094bb2077c7998ef663d5545e9a3e18d03

src/com/android/settings/fuelgauge/PowerUsageBase.java

@@ -72,8 +72,6 @@ public abstract class PowerUsageBase extends DashboardFragment {
     @Override
     public void onResume() {
         super.onResume();
-
-        BatteryStatsHelper.dropFile(getActivity(), BatteryHistoryDetail.BATTERY_HISTORY_FILE);
         mBatteryBroadcastReceiver.register();
     }