Remove persistence from the kauth helper
Summary:
The way the helper works allows everyone with access to elevate to root
trivially, so persistence needs to be avoided.
Test Plan: .policy file has auth_admin now.
Reviewers: Plasma, davidedmundson, filipf, ngraham
Reviewed By: ngraham
Subscribers: plasma-devel
Tags: Plasma
Differential Revision: https://phabricator.kde.org/D23078