Move KGamma's KCMInit work to phase 1 of login.

Summary:
Phase 0 is already after the splash screen is up, so the visual
change will occur during startup either way. It doesn't make
sense to wait around for it during phase 0.

Reviewers: Plasma, davidedmundson

Subscribers: plasma-devel

Tags: Plasma

Differential Revision: https://phabricator.kde.org/D9179