This Magento 2 module adds all non-Magento root menu-items of the admin menu to a menu-item "Third Party". It doesn't use JavaScript to do this, but cleanly hooks into the model-class used by the core.
Install this package via composer:
composer require yireo/magento2-clean-admin-menuNext, enable this module:
bin/magento module:enable Yireo_CleanAdminMenu