[server] Reorder Express routers

Summary: The order of these matters - see code comment.

Test Plan: I actually tested reordering these live on prod, and it worked

Reviewers: varun

Reviewed By: varun

Subscribers: palys-swm, Adrian, atul, karol-bisztyga, benschac, yayabosh

Differential Revision: https://phabricator.ashoat.com/D3572