[4.0] Empty Trash (#21602)

Makes the empty-trash button red just as the delete button is

Author: brianteeman

libraries/src/Toolbar/Button/StandardButton.php

@@ -118,6 +118,7 @@ public function fetchButtonClass(string $name): string
 				return ' btn btn-sm btn-danger';
 
 			case 'trash':
+			case 'delete':
 				return ' btn btn-sm btn-danger';
 
 			default: