minor symfony#12571 Remove unused imports (toniperic)

This PR was merged into the 4.3 branch.

Discussion
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Remove unused imports

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Commits
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7de6bfc Remove unused imports

Author: OskarStark

bundles/extension.rst

@@ -119,10 +119,6 @@ they are compiled when generating the application cache to improve the overall
 performance. Define the list of annotated classes to compile in the
 ``addAnnotatedClassesToCompile()`` method::
 
-    use App\Manager\UserManager;
-    use App\Utils\Slugger;
-
-    // ...
     public function load(array $configs, ContainerBuilder $container)
     {
         // ...