Do not add icons to media viewer image list

e.g. {{refimprove}} on enwiki - there is an icon of a book that is only
meant to be illustrative on the page. It interferes with the page's image
collection and the flow.

Change-Id: Icd7e5885aaf8b31fffe07bd18cc0feb0f76b848c
Mingle: https://wikimedia.mingle.thoughtworks.com/projects/multimedia/cards/229
Merge "Do not add icons to media viewer image list"