Don't add colons to wikilinks inside of {{Draft categories}}

[NovemLinguae]

Requested by InfiniteNexus at https://en.wikipedia.org/wiki/Wikipedia_talk:WikiProject_Articles_for_creation#Category_links

AFCH automatically adds colons to [[Category:abc]] type wikilinks so that drafts stay out of categories. So [[Category:abc]] is converted to [[:Category:abc]]

This ticket is to code an exception for categories inside of the template {{Draft categories}}. Apparently these colons are not needed in there.

Diff of incorrect AFCH behavior: https://en.wikipedia.org/w/index.php?diff=1137264750&diffmode=source