service_contexts

Applications do not explicitly request handles to the batteryproperties
service, but the BatteryManager obtains a reference to it and uses it
for its underlying property queries.  Mark it as an app_api_service so
that all applications may use this API.  Also remove the batterypropreg
service label, as this does not appear to be used and may have been a
duplication of batteryproperties.  As a result, remove the
healthd_service type and replace it with a more specific
batteryproperties_service type.

Bug: 27442760
Change-Id: I5c0f9d7992ff2ec64adaeef22356e88fd0e8169c