Geo: Fix devise routes on primary site

What does this Merge Request do and why?

Fixes a sign in problem (and a sign out problem).

This MR won't have an effect until gitlab!88179 (merged). Prefer to merge this first, but ok if not as long as there is no change in the approach.

Part of gitlab#362850 (closed)

Merge Request checklist

• This change is backward compatible. If not, please include steps to communicate to our users.
• [-] Tests added for new functionality. If not, please raise Issue to follow-up.
• [-] Documentation added/updated, if needed.
• [-] gdk doctor test added, if needed.
• [-] Add the ~highlight label if this MR should be included in the CHANGELOG.md.