magento-test/app/code/Magento/Backend/view/adminhtml/templates/pageactions.phtml

<?php
/**
 * Copyright © Magento, Inc. All rights reserved.
 * See COPYING.txt for license details.
 */
?>
<?php if ($block->getChildHtml()) :?>
    <div data-mage-init='{"floatingHeader": {}}' class="page-actions floating-header" <?= /* @noEscape */ $block->getUiId('content-header') ?>>
        <?= $block->getChildHtml() ?>
    </div>
<?php endif; ?>