Removed X-Images variance & legacy url params

* X-Images variance is never used anywhere, and cannot be
  set in varnish without hardcoding X-CS knowledge or a lookup table
* render* url params are no longer used, and should not exist in cache

Change-Id: I397049e0b796bc2b432de9e6b4a1d7e35fa7b071
Merge "Removed X-Images variance & legacy url params"