Use DataSync for issue promotion

What does this MR do and why?

Use the new DataSync services to clone issues to epics. Since it copies over notes in batches, it should help with the timeouts we see when promoting issues that have lots of notes.

It also fixes an old bug where we duplicate the "added label", and "added parent" system notes.

Issue: #556211 (closed)

References

Screenshots or screen recordings

promote

Before	After

How to set up and validate locally

• Enable use_data_sync_for_issue_promotion feature flag
• Create an issue, or use an existing one
• Use /promote_to Epic quick action, or change the type of the work item to Epic (which promotes it)

MR acceptance checklist

Evaluate this MR against the MR acceptance checklist. It helps you analyze changes to reduce risks in quality, performance, reliability, security, and maintainability.