Sync epic work item on issue promotion

What does this MR do and why?

Sync epic work item on issue promotion

This ensures that we create a new epic work item when an issue gets promoted and also set the same attributes.

Part of #434530 (closed)

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Before	After

How to set up and validate locally

1. Enable epic_creation_with_synced_work_item and namespace_level_work_items feature flags
2. Go to a project and create an issue, or use an existing issue
3. Promote the issue to an epic
4. Check if the promoted epic has a correlating work item with the same description by replacing /epics/ with /work_items/ in the URL