Group Migration - 'Epic label(s) added/removed' events missing
<!--IssueSummary start-->
<details>
<summary>
Everyone can contribute. [Help move this issue forward](https://handbook.gitlab.com/handbook/marketing/developer-relations/contributor-success/community-contributors-workflows/#contributor-links) while earning points, leveling up and collecting rewards.
</summary>
- [Work on this issue](https://contributors.gitlab.com/manage-issue?action=work&projectId=278964&issueIid=354705)
- [Close this issue](https://contributors.gitlab.com/manage-issue?action=close&projectId=278964&issueIid=354705)
</details>
<!--IssueSummary end-->
## Problem to solve
During Group Migration, any events on epics regarding labels added or removed are currently not migrated.
This may be confusing to users as they may rely on this information for audit and research purposes.
## Screenshots


## Proposed solution
Migrate the "labels added" and "labels removed" events for epics.
issue