[kcm] Remove profiles code

Summary:
This code seems to be unused for a long time or was never used at all.
Introduced in 2013 there were no substantial commits to it afterwards,
nor is the functionality exposed to the Ui.

Test Plan: Compiles.

Reviewers: Plasma, apol, davidedmundson

Reviewed By: Plasma, apol, davidedmundson

Subscribers: davidedmundson, afiestas, apol, dvratil, plasma-devel

Tags: Plasma

Differential Revision: https://phabricator.kde.org/D16898