Fix sorting error

We need to remove the _ before id, domain or key to avoid this kind of errors:

CRITICAL: Uncaught PHP Exception Doctrine\ORM\Query\QueryException: "[Semantical Error] line 0, col 5355 near '_domain asc': Error: Class Lexik\Bundle\TranslationBundle\Entity\TransUnit has no field or association named _domain" at /srv/ic2m/novento/vendor/doctrine/orm/lib/Doctrine/ORM/Query/QueryException.php line 63 {"exception":"[object] (Doctrine\\ORM\\Query\\QueryException: [Semantical Error] line 0, col 5355 near '_domain asc': Error: Class Lexik\\Bundle\\TranslationBundle\\Entity\\TransUnit has no field or association named _domain at /srv/ic2m/novento/vendor/doctrine/orm/lib/Doctrine/ORM/Query/QueryException.php:63, Doctrine\\ORM\\Query\\QueryException: SELECT tu.id FROM Lexik\\Bundle\\TranslationBundle\\Entity\\TransUnit tu WHERE tu.id