drop ancient commented out code

Summary:
it's been disabled since 2013. it stands to reason that we don't need it
and should we need it in the future I am sure we'll manage to figure out
how to use kaboutdata...

Reviewers: Plasma, ivan, mart

Reviewed By: Plasma, mart

Subscribers: plasma-devel

Tags: Plasma

Differential Revision: https://phabricator.kde.org/D17118