Add audit events for merge request settings

What does this MR do and why?

Captures audit events for following settings

• Merge commit message template (this is part of Part 1 #301124 (closed) so we can skip this in Part 2)
• Squash commit message template
• Default description template for merge requests
• Status checks added / edited / deleted

Screenshots or screen recordings

Squash options:

How to set up and validate locally

1. Run GDK
2. Go to Projects Settings -> General and Expand Merge requests.
3. Add, Edit, Delete Status check, Squash commit message template, Default description template for merge requests, Default description template for merge requests
4. Check audit events (admin/audit_events or project//-/audit_events) for every action (add, edit, delete)

Related to #355805 (closed)