[DoctrineBundle] removed unneeded parameter definition

src/Symfony/Bundle/DoctrineBundle/Resources/config/dbal.xml

@@ -5,7 +5,6 @@
     xsi:schemaLocation="http://symfony.com/schema/dic/services http://symfony.com/schema/dic/services/services-1.0.xsd">
 
     <parameters>
-        <parameter key="doctrine.dbal.default_connection">default</parameter>
         <parameter key="doctrine.dbal.connection.class">Doctrine\DBAL\Connection</parameter>
         <parameter key="doctrine.dbal.logger.debug.class">Doctrine\DBAL\Logging\DebugStack</parameter>
         <parameter key="doctrine.dbal.logger.class">Symfony\Bundle\DoctrineBundle\Logger\DbalLogger</parameter>