Hoist duplicated AlarmService initialization to super

api_client and _load_evaluators was duplicated across each service,
presumably needlessly*.

Discovered via pylint complaining about use of unitialize api_client
member.

* If there is a specific need for it to be otherwise that needs to
be made more clear.

Change-Id: I118edce87abd0e26ee0e963f44535b355a3752d0
Merge "Hoist duplicated AlarmService initialization to super"