HOLD: Hide erroneous featured comments

Small tweak to hide unfeatured comments from featured box when they've been returned by a cached VIP query.

https://github.com/GigaOM/gigaom/issues/5097
https://github.com/GigaOM/gigaom/issues/5104

Related:
https://github.com/GigaOM/gigaom-plugins/pull/2536