minor #22825 [DI] Remove dead service_container checks (ro0NL)

This PR was merged into the 3.3 branch.

Discussion
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[DI] Remove dead service_container checks

| Q             | A
| ------------- | ---
| Branch?       | 3.3
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #... <!-- #-prefixed issue number(s), if any -->
| License       | MIT
| Doc PR        | symfony/symfony-docs#... <!--highly recommended for new features-->

Since #21627

Commits
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9a8ea93 [DI] Remove dead service_container checks

Author: nicolas-grekas

Dumper/GraphvizDumper.php

@@ -192,8 +192,7 @@ private function findNodes()
             }
 
             if (!$container->hasDefinition($id)) {
-                $class = get_class('service_container' === $id ? $this->container : $container->get($id));
-                $nodes[$id] = array('class' => str_replace('\\', '\\\\', $class), 'attributes' => $this->options['node.instance']);
+                $nodes[$id] = array('class' => str_replace('\\', '\\\\', get_class($container->get($id))), 'attributes' => $this->options['node.instance']);
             }
         }