Add a check to use the different URL for namespace

What does this MR do and why?

The MR solves the bug by checking for the link being generated for a user namespace when they are out of limits and pointing it to 'https://customers.gitlab.com/buy_pipeline_minutes'.

Screenshots or screen recordings

Before	After

How to set up and validate locally

1. Run jobs using shared runners and deplete the 400 units of compute provided
2. Wait for the "Action required" letter
3. Click "Buy more Pipeline minutes → " link

Related to #377876 (closed)