Summary: "Edit Panel..." already enters the edit mode, so there's no need to clutter the context menu with another "Customize Layout..." menu item.
Test Plan: Open the panel context menu.
Reviewers: #plasma, #vdg, mart, ngraham
Reviewed By: #plasma, #vdg, mart, ngraham
Subscribers: mart, #vdg, plasma-devel, #plasma
Tags: #plasma
Differential Revision: https://phabricator.kde.org/D25053