Make the tracing test work without Doctrine too

Author: Jean85

tests/End2End/App/Controller/TracingController.php

@@ -10,18 +10,20 @@
 class TracingController
 {
     /**
-     * @var Connection
+     * @var Connection|null
      */
     private $connection;
 
-    public function __construct(Connection $connection)
+    public function __construct(Connection $connection = null)
     {
         $this->connection = $connection;
     }
 
     public function pingDatabase(): Response
     {
-        $this->connection->executeQuery('SELECT 1');
+        if ($this->connection) {
+            $this->connection->executeQuery('SELECT 1');
+        }
 
         return new Response('Success');
     }

tests/End2End/App/tracing.yml

@@ -7,6 +7,6 @@ sentry:
 services:
   Sentry\SentryBundle\Tests\End2End\App\Controller\TracingController:
     arguments:
-      - '@doctrine.dbal.default_connection'
+      - '@?doctrine.dbal.default_connection'
     tags:
       - controller.service_arguments