Resolve "Lazy image loading breaks notification mails for an added screenshot"

What does this MR do?

It fixes the notification mail images as they were also rendered with lazy loading. I simply look now for the path variable set in the email filter.

Tested it by looking at generated output in development.log :

Why was this MR needed?

So images are visible again in notificaiton emails.

Screenshots (if relevant)

chrome_2017-09-11_11-42-40

Does this MR meet the acceptance criteria?

What are the relevant issue numbers?

Closes #37629 (closed)

Edited by Tim Zallmann