Depending on the kind of config error being shown, different "go back"
links may be more appropriate.
We probably hard-coded /login/ for it, because these config errors are
most commonly used for authentication backend config error, where it
makes sense to have /login/ as "go back", because the user most likely
indeed got there from the login page.
However, for remote_billing_bouncer_not_configured, it doesn't make
sense, because the user almost surely is already logged in and got there
by clicking "Plan management" inside the gear menu in the logged in app.