Remove UpdateLockedUnknownArtifactsWorker

What does this MR do and why?

Resolves #439508

Remove UpdateLockedUnknownArtifactsWorker

This worker was added to backfill locked status on job artifacts. All expired job artifacts that had unknown locked status have since been backfilled and this worker has not been updating any more records as seen in the Kibana logs.

https://log.gprd.gitlab.net/app/r/s/PgBo1

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Related to #356319