Only call VirtualDesktops::load once
It was called twice once with and without X as our implementation of setRootInfo() missed some calls.
This was done to avoid a bug as setRootInfo() didn't update everything. This patch aims to resolve that at the root cause.
I tested the original conditions of the patch with an empty kwinrc and a file in /etc/xdg/kwinrc setting desktops to 2 and everything loaded correctly.