Revert "Issue #3351162 by alexahumada: Undefined array key "" in...

Revert "Issue #3351162 by alexahumada: Undefined array key "" in Drupal\layout_builder_browser\Form\BlockForm"

This reverts commit c6040f2f.

src/Form/BlockForm.php

@@ -49,8 +49,7 @@ class BlockForm extends EntityForm {
     foreach ($definitions as $id => $definition) {
       $category_id = $category_label = $definition['category'];
       if ($definition['category'] instanceof TranslatableMarkup) {
-        $category_id = $definition['category']->getUntranslatedString();
-        $category_label = $definition['category']->render();
+        $category_id = $category_label = $definition['category']->render();
       }
 
       $blocks[$category_id][$id] = $definition['admin_label'];