Fix /w redirect for /wiki MediaWiki URL scheme

Summary:
www.wolfplex.org has been hardcoded, perhaps moving a rule from
the www.wolfplex.org server block to the MediaWiki include config

As such, on other wikis, https://wiki/w redirected to Wolfplex wiki.

This is a follow-up to change 07522e6aa211.

Test Plan: Browse https://utopia.espace-win.org/w

Reviewers: dereckson

Reviewed By: dereckson

Differential Revision: https://devcentral.nasqueron.org/D1510