Clean up artifact expiry migration problem

What does this MR do?

Comments out the scheduling code in the migration introduced with !47723 (merged) as it was raising errors due to a wrong parameter type provided to queue_background_migration_jobs_by_range_at_intervals. It also removes any pending jobs scheduled with !47723 (merged)

The scheduling will be re-introduced correctly with !51822 (merged)

Related #298813 (closed)

Does this MR meet the acceptance criteria?

Conformity

• N/A Changelog entry
• N/A Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• N/A Separation of EE specific content