Mark batteryproperties service as app_api_service.

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.

(cherry-picked from commit: 9ed71eff4bed91653cba393ea6cb42f041d4e257)

Bug: 27442760
Change-Id: I537c17c09145b302728377bf856c1147e4cc37e9
diff --git a/service_contexts b/service_contexts
index 681521d..8bd4e0c 100644
--- a/service_contexts
+++ b/service_contexts
@@ -10,8 +10,7 @@
 assetatlas                                u:object_r:assetatlas_service:s0
 audio                                     u:object_r:audio_service:s0
 backup                                    u:object_r:backup_service:s0
-batteryproperties                         u:object_r:healthd_service:s0
-batterypropreg                            u:object_r:healthd_service:s0
+batteryproperties                         u:object_r:batteryproperties_service:s0
 batterystats                              u:object_r:batterystats_service:s0
 battery                                   u:object_r:battery_service:s0
 bluetooth_manager                         u:object_r:bluetooth_manager_service:s0