remove unnecessary monkey patch for activejob test helpers
remove unnecessary monkey patch for activejob test helpers

A bespoke active job helper was overridin methods
that are usable from the ActiveJob::TestHelper
module.

ministryofjustice/peoplefinder,ministryofjustice/peoplefinder,ministryofjustice/peoplefinder,ministryofjustice/peoplefinder,ministryofjustice/peoplefinder