Fix docs review app script and domain

What does this MR do?

I made a typo in the review app domain, so docs reviews aren't reporting the correct URL.

Actually, I now realize that review apps have been broken for a long time. They were fixed in omnibus-gitlab with omnibus-gitlab!5989 (merged), so this repeats that fix as well.

Why was this MR needed?

What's the best way to test this MR?

What are the relevant issue numbers?