Use classic static.guim.co.uk as original image for articles where possible.

Trawling forums indicates that it is possible that Google News does not pick up images from a CDN https://productforums.google.com/forum/#!topicsearchin/news/cdn$20images

It seems possible it only picks up images from domains it trusts (e.g. over time, or it has been asked to trust them).

We know it picks up images from static.guim.co.uk, so this is a test to check that hypotheses.

It will only use static.guim.co.uk if there is an exct match for the width.
Merge pull request #4699 from guardian/thumbnail

Use classic static.guim.co.uk as original image for articles if possible