Fix sticky battery saver toggle

It was persisting to settings secure instead of settings global.

Test: robotests pass
Bug: 128929858
Change-Id: I8c5bcc875d71096e70f1a70ec84e85d46c3abe43

tests/robotests/src/com/android/settings/fuelgauge/batterysaver/BatterySaverStickyPreferenceControllerTest.java

@@ -42,7 +42,7 @@ public class BatterySaverStickyPreferenceControllerTest {
     }
 
     private int getAutoDisableSetting() {
-        return Settings.System.getInt(mContext.getContentResolver(),
+        return Settings.Global.getInt(mContext.getContentResolver(),
                 LOW_POWER_STICKY_AUTO_DISABLE_ENABLED,
                 1);
     }