[2.7] [Form] Replaced calls to array_search() by in_array() where is no need to get the index

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | none
| License       | MIT
| Doc PR        | none

Author: phansys

Extension/Core/ChoiceList/ChoiceList.php

@@ -381,7 +381,7 @@ protected function addChoice(array &$bucketForPreferred, array &$bucketForRemain
      */
     protected function isPreferred($choice, array $preferredChoices)
     {
-        return false !== array_search($choice, $preferredChoices, true);
+        return in_array($choice, $preferredChoices, true);
     }
 
     /**

Extension/Core/Type/ChoiceType.php

@@ -111,7 +111,7 @@ public function buildView(FormView $view, FormInterface $form, array $options)
         // avoid making the type check inside the closure.
         if ($options['multiple']) {
             $view->vars['is_selected'] = function ($choice, array $values) {
-                return false !== array_search($choice, $values, true);
+                return in_array($choice, $values, true);
             };
         } else {
             $view->vars['is_selected'] = function ($choice, $value) {