Replace `className="secondary"` by `variant="secondary"` (#21672)

GitOrigin-RevId: a45532c2b4e927c3cc3a771eaf185ced4650f94c

services/web/frontend/js/features/file-tree/components/modals/file-tree-modal-delete.jsx

@@ -63,7 +63,7 @@ function FileTreeModalDelete() {
           />
         ) : (
           <>
-            <OLButton className="secondary" onClick={handleHide}>
+            <OLButton variant="secondary" onClick={handleHide}>
               {t('cancel')}
             </OLButton>
             <OLButton variant="danger" onClick={handleDelete}>