title: Symfony4.3 Sorting preferred choices provided by query builder in EntityType
body: <p>I have a selection of events provided by query builder. All entities have to be shown in the selection field, using the future events as preferred choices. Both parts should be sorted by date (asc). 
  Till now it worked fine the following way:</p>
  
  <pre><code>-&gt;add('event', EntityType::class, array(
      'class'        =&gt; 'App:Event',
      'choice_label' =&gt; 'name',
      'expanded'  =&gt; false,
      'multiple'  =&gt; false,
      'required' =&gt; false,
      'placeholder' =&gt; '-',
      'query_builder' =&gt; function (EntityRepository $er) {
          return $er-&gt;createQueryBuilder('e')
              -&gt;orderBy('e.date', 'ASC');
      },
      'preferred_choices' =&gt; function ($event) {
          if($event-&gt;getDate() &gt; new \DateTime()){
              return true;
          }
          return false;
      }
  ))
  </code></pre>
  
  <p>Since the update to Symfony 4.3 the sort order of the preferred choices is no longer kept, as described here:
  <a href="https://github.com/symfony/symfony/pull/30985" rel="nofollow noreferrer">https://github.com/symfony/symfony/pull/30985</a>
  I've no array of the preferred choices, as I use a callable to decide which event is in the future. How can I sort the preferred choices now? I couldn't find any clue for that in the changing description.
  Is there really no longer any other way than creating an array of events outside the formbuilder?</p>