In systemsettings 6a9df821ecfaa008206a260b20f595136e254821 it was
determined that the QML KCMs should do their own padding for some
reason.
QML KCMs now do this to match what's expected in system settings.
This change was not mirrored in KMultiDialog (and hence kcmshell5)
Populating d->modules had to move in order to make sure this was
available when the first page was added.