🐛 Fix custom thumbnail showing on searches

[kirkkwang]

Story

This commit will remove a Hyrax override that seemed to be causing some issues with the search list view and also bring in a fix from PALs with to address the search gallery view.

Ref:

• https://github.com/scientist-softserv/atla-hyku/issues/122
• https://github.com/scientist-softserv/palni-palci/pull/540

Expected Behavior Before Changes

Custom thumbnails were not showing up in list and gallery search views.

Expected Behavior After Changes

Custom thumbnails now show up correctly.

Screenshots / Video

List view:

Gallery view: