Fix link to Jira service documentation

What does this MR do?

It fixes the link to JIRA documentation that is being displayed on JIRA Service Settings page.

Why was this MR needed?

The link was to a page that has been moved.

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated
• API support added
• Tests
  • Added for this feature/bug
  • All builds are passing
• Conform by the merge request performance guides
• Conform by the style guides
• Branch has no merge conflicts with master (if it does - rebase it please)
• Squashed related commits together

What are the relevant issue numbers?

Closes #29929 (closed)