Refresh open Issue and Merge Request project counter caches when re-opening

What does this MR do?

Refreshes open Issue and Merge Request project counter caches when re-opening them.

Are there points in the code the reviewer needs to double check?

app/services/merge_requests/reopen_service.rb and app/services/issues/reopen_service.rb

Why was this MR needed?

Bug fix

Screenshots (if relevant)

n/a

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• 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

What are the relevant issue numbers?

Closes #39583 (closed)