minor #14217 Missed cleanup in fluent migration (greg0ire)

This PR was squashed before being merged into the 4.4 branch.

Discussion
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Missed cleanup in fluent migration

Commits
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1a9c48e Missed cleanup in fluent migration

Author: javiereguiluz

cache.rst

@@ -567,9 +567,6 @@ to enable this feature. This could be added by using the following configuration
     .. code-block:: php
 
         // config/packages/cache.php
-        use Symfony\Component\Cache\Adapter\ChainAdapter;
-        use Symfony\Component\DependencyInjection\Reference;
-
         $container->loadFromExtension('framework', [
             'cache' => [
                 'pools' => [

reference/configuration/swiftmailer.rst

@@ -381,7 +381,6 @@ alternatives based on the :ref:`service binding <services-binding>` feature:
         // config/services.php
         use App\Some\Service;
         use Psr\Log\LoggerInterface;
-        use Symfony\Component\DependencyInjection\Reference;
 
 
         $container->register(Service::class)

service_container.rst

@@ -483,7 +483,7 @@ all their types (string, boolean, array, binary and PHP constant parameters).
 However, there is another type of parameter related to services. In YAML config,
 any string which starts with ``@`` is considered as the ID of a service, instead
 of a regular string. In XML config, use the ``type="service"`` type for the
-parameter and in PHP config use the ``Reference`` class:
+parameter and in PHP config use the ``ref`` function:
 
 .. configuration-block::