Don't show entries with NoDisplay=true with the applauncher containmentaction

Summary: Currently NoDisplay services are shown, which doesn't make much sense.

Test Plan: Installed and looked through the menu, no excessive or duplicate items anymore.

Reviewers: #plasma, hein

Reviewed By: #plasma, hein

Subscribers: plasma-devel

Tags: #plasma

Differential Revision: https://phabricator.kde.org/D19157