open non-impact story testimonial links in not a lightbox

[TomWoodward]

https://openstax.atlassian.net/browse/DISCO-436

there was also a bug here where it was loading the stories O(n^2) times

~need to see if i can make the cms know the correct url for the page....~ done in https://github.com/openstax/openstax-cms/pull/1579