Skip validation for derivative containers

DerivativeContainerFactory creates secondary containers (e.g. for stub
validation) that have different source locators. These containers set
__validate to false, so use the same guard as validateParameters.

Co-Authored-By: Claude Code

Author: janedbal

src/DependencyInjection/ContainerFactory.php

@@ -371,6 +371,10 @@ private function validateParameters(array $parameters, array $parametersSchema):
 	 */
 	private function validateExceptionClasses(ReflectionProvider $reflectionProvider, array $parameters): void
 	{
+		if (!(bool) $parameters['__validate']) {
+			return;
+		}
+
 		if (
 			!array_key_exists('featureToggles', $parameters)
 			|| !is_array($parameters['featureToggles'])