[Bug]: copyRecursive fails on copying a folder with emails (pimcore#1…

…7758)

* fix: getChildren returns null values form cache

* fix: remove unnecessary import

models/Element/Service.php

@@ -567,7 +567,7 @@ protected function updateChildren(DataObject|Document|Asset\Folder $target, Elem
     {
         //check in case of recursion
         $found = false;
-        foreach ($target->getChildren() as $child) {
+        foreach ($target->getChildren()->load() as $child) {
             if ($child->getId() == $new->getId()) {
                 $found = true;