recovery uses IHealth::getService

recovery is_battery_ok function uses get_health_service(),
which calls IHealth::getService("default") then
IHealth::getService("backup").

- An OEM can provide the default instance by installing
  android.hardware.health@2.0-impl-<device>.so to recovery
  partition.

- If that's not found, the "backup" instance is provided
  to the recovery partition by default.

Test: call is_battery_ok() in recovery, successfully
  get battery information.

Bug: 80132328

Change-Id: Ibfee80636325a07bc20b24d044d007a60b3dd7c2