Remove obsolete imagescaler logic from swift proxy

Authored by Muehlenhoff on Apr 6 2018, 2:04 PM.

Description

Remove obsolete imagescaler logic from swift proxy

This refers to the previous image scaling setup (based on mediawiki) which
was replaced by Thumbor.

Bug: T188062
Change-Id: I9bfa49c8cf3023dce396b5167e8a9bdb16046396