Fix choice_label compatibility with Symfony < 8.1

Don't pass null choice_label explicitly to EntityType as it behaves
differently than omitting the option in older Symfony versions.

Author: Amoifr

src/Form/EventListener/CrudAutocompleteSubscriber.php

@@ -70,6 +70,12 @@ public function preSetData(FormEvent $event)
             $options['autocomplete_template']
         );
 
+        // Don't pass null choice_label to EntityType - let it use __toString() default
+        // (passing null explicitly behaves differently than omitting the option in Symfony < 8.1)
+        if (null === ($options['choice_label'] ?? null)) {
+            unset($options['choice_label']);
+        }
+
         $form->add('autocomplete', EntityType::class, $options);
     }