Create issue and merge request destroy services

What does this MR do?

Creates a service for destroying issues and merge requests.

Why was this MR needed?

In order to have a centralized service for issuable destruction

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• [n/a] Documentation created/updated
• API support added
• Tests added for this feature/bug
• Review
  • Has been reviewed by UX
  • Has been reviewed by Frontend
  • Has been reviewed by Backend
  • Has been reviewed by Database
• Conform by the merge request performance guides
• Conform by the style guides
• Squashed related commits together
• [n/a] Internationalization required/considered

What are the relevant issue numbers?

Closes #39601 (closed)