Remove ModelAutocompleteType::getParent override

This override is useless because it's the default behavior of
Symfony\Component\Form\AbstractType

Form/Type/ModelAutocompleteType.php

@@ -150,14 +150,6 @@ class ModelAutocompleteType extends AbstractType
         $resolver->setRequired(array('property'));
     }
 
-    /**
-     * {@inheritdoc}
-     */
-    public function getParent()
-    {
-        return 'form';
-    }
-
     /**
      * {@inheritdoc}
      */