[REF] Minor cleanup around actionn schedule code.

[REF] Minor cleanup around actionn schedule code.

CRM_Core_BAO_ActionSchedule::processQueue is only called from one place. It either succeeds or throws
an exception so there is no value in returning anything & the parsing of what it does return assumes that it
could return false

Some slight tightenig around typing as buildRecipientContact is also only called from one place