Change parent link reference when issue moves

What does this MR do and why?

We did not change the reference of a parent link when we moved an issue and with it also changed the epic_issues reference.

This MR fixes the problem by also changing the associated ParentLink reference using the new issue.

Issue: #465459 (closed)

MR acceptance checklist

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Screenshots or screen recordings

1. Create Parent Epic
2. Add an issue to Parent Epic like Issue 1 in Project A
3. Move the Issue 1 to Project B
4. Go to the Parent Epic and remove the relationship with Issue 1

Before	After

How to set up and validate locally

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