Remove location_modes_previous references

1. Remove reference to LOCATION_MODE_PREVIOUS.

2. Add setLocationEnabled method in LocationEnabler. When turning location
ON/OFF from Settings app or Quick Settings, use
LocationEnabler.setLocationEnabled() instead of setLocationMode().

3. Change unit tests accordingly.

Bug: 70990911
Test: Robolectric
Test: Manual
Change-Id: Ic02ef3cd02f9aa7d2ef18697b19b507575aaf5c2

src/com/android/settings/location/LocationSwitchBarController.java

@@ -96,9 +96,6 @@ public class LocationSwitchBarController implements SwitchBar.OnSwitchChangeList
      */
     @Override
     public void onSwitchChanged(Switch switchView, boolean isChecked) {
-        mLocationEnabler.setLocationMode(isChecked
-                ? android.provider.Settings.Secure.LOCATION_MODE_PREVIOUS
-                : android.provider.Settings.Secure.LOCATION_MODE_OFF);
+        mLocationEnabler.setLocationEnabled(isChecked);
     }
-
 }