image optimization only works on /hlx_ blobs

[davidnuescheler]

it seems that image optimization is either not configured or not turned on for anything that is not a helix blob served with the /hlx_ prefix. is something is served statically it doesn't seem to go through the image optimization service (or at least the ?width= query parameters don't do anything.

compare:

https://blog.adobe.com/icons/scan-documents.png?width=128

vs.

https://blog.adobe.com/hlx_6308ccba2039f18bd0a90455b2f158e297defb38.jpeg?width=128