Bug 21225: (follow-up) Account for Syndetics lightbox

Bug 21225: (follow-up) Account for Syndetics lightbox

To test:
-Make sure when you apply all the patches that when you click on the Syndetics image in the detail page that it correctly displays the lightbox.
-Turn on some other cover image services and make sure you can toggle through each of them.

Signed-off-by: Barbara Johnson <barbara.johnson@bedfordtx.gov>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>