remove misc::download-mediawiki from kaulen because it's either
supposed to be on swift or on a new download host in eqiad, but not
on the bugzilla server and not in Tampa and it wasn't used anyways.
just added download.mediawiki.org to Apache conf so that at least
it wasn't just showing an empty directory on kaulen but redirects
to mediawiki.org

Change-Id: Idb8b6f90cb5400ee2227b9ed3b5c1ed97d176bd4