The entry X-KDE-DBus-ModuleName has never been used by kded code,
at least is not using it these days, so the check for that metadata entry
and using its value is broken.
Instead Kded::loadModule() used KPluginMetaData::pluginId() to set the
module name, which then is used by KDEDModule for its D-Bus object path.
The branch for handling an empty name is removed as that fallback is
covered by KPluginMetaData already.