Fix "Plasma Renderer" KCM not being launchable
BUG: 421431
FIXED-IN: 5.20
As described in https://phabricator.kde.org/D7934#251757 this KCM should not show up in systemsettings, but it should be launchable using KRunner. That is why the category hidden was choosen as sort of a dummy value (from my interpretation). But the services runner replaces the Exec line and uses systemsettings instead of kcmshell. And because of the dummy value the fix for Bug: 423612 does not apply here. So we just have to remove it ;)