minor #19736 [FrameworkBundle][Security] Remove useless mocks (Ener-Getick)

This PR was merged into the 2.7 branch.

Discussion
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[FrameworkBundle][Security] Remove useless mocks

| Q             | A
| ------------- | ---
| Branch?       | 2.7
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets |
| License       | MIT
| Doc PR        |

Removes mocks causing issues in symfony/symfony#19734.

Commits
-------

fcd3345 [FrameworkBundle][Security] Remove useless mocks

Author: fabpot

Tests/Templating/DelegatingEngineTest.php

@@ -12,6 +12,7 @@
 namespace Symfony\Bundle\FrameworkBundle\Tests\Templating;
 
 use Symfony\Bundle\FrameworkBundle\Templating\DelegatingEngine;
+use Symfony\Component\HttpFoundation\Response;
 
 class DelegatingEngineTest extends \PHPUnit_Framework_TestCase
 {
@@ -60,7 +61,7 @@ public function testGetInvalidEngine()
 
     public function testRenderResponseWithFrameworkEngine()
     {
-        $response = $this->getMock('Symfony\Component\HttpFoundation\Response');
+        $response = new Response();
         $engine = $this->getFrameworkEngineMock('template.php', true);
         $engine->expects($this->once())
             ->method('renderResponse')