[Settings] Refactor AirplaneModeEnabler

1. Multiple instance of PhoneStateListener is not required.
2. It will be better to monitor radio power state changed instead of service state.

Bug: 147029746
Test: Manual
Test: make RunSettingsRoboTests -j ROBOTEST_FILTER=AirplaneModePreferenceControllerTest
Change-Id: I51465904ce2409b6c07c3ba80ea362d208989fbd