Fix external issue tracker "Issues" link leading to 404s

## What does this MR do?

This MR fixes the redirection to the wrong URL when using an external issue tracker, such as JIRA or Redmine.  a70431f8 modified the behavior to link to the external issue tracker
issues URL instead of the project path URL. This restores the previous behavior.

## Why was this MR needed?

The issues URL often has `:id` associated with it for linking mentioned issues.
For external issue trackers, the project page is the intended target.

## What are the relevant issue numbers?

Closes #21252

Related to #21402

See merge request !6006