Links for Redmine issue references are generated correctly again

What does this MR do?

This MR contains fixes for #14527 (closed). References to Redmine issues in merge request descriptions were not displayed as links, but as plain text.

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

Check that the confidential issues are still working as expected.

Why was this MR needed?

This MR is needed because confidential issues broke the link generation for Redmine issues.

What are the relevant issue numbers?

#14527 (closed), #14894 (closed)

Closes #14527 (closed) and closes #14894 (closed)