[Applets/Kickoff] Show apps by their real names on top by default

Summary:
Right now Kickoff shows apps' captions/subtitles on top, with the real name below them.
This is semantically backwards and is also inconsistent with the order with which app
names and captions/subtitles are presented in most other places (Task Manager tooltips,
other launchers, other desktop environments, other operating systems).

This patch reverses the default ordering to put app names on top and fix the above issues.

IMO it would even make sense to remove this option and its code entirely, and we could
still do that, but I just wanted to flip the default for now to avoid undue controversy. I can
remove the option and code if people agree with the reasoning behind this patch and
prefer that.

Test Plan: App names are now on top by default with captions/subtitles below them

Reviewers: #vdg, #plasma, ndavis

Reviewed By: #vdg, ndavis

Subscribers: meven, ndavis, michaeltunnell, plasma-devel

Tags: #plasma

Differential Revision: https://phabricator.kde.org/D25838