minor #39931 Use class const in test (OskarStark)

This PR was merged into the 5.1 branch.

Discussion
----------

Use class const in test

| Q             | A
| ------------- | ---
| Branch?       | 5.1
| Bug fix?      | no
| New feature?  | no
| Deprecations? | no
| Tickets       | ---
| License       | MIT
| Doc PR        | ---

super minor, same as #39930, but for `5.1`

I will finish this PR after #39930 is merged and upmerged

Commits
-------

4a98eeecdc [Security] [HttpFoundation] Use class const in test

src/Symfony/Component/Security/Http/Tests/Authenticator/FormLoginAuthenticatorTest.php

@@ -13,6 +13,7 @@ namespace Symfony\Component\Security\Http\Tests\Authenticator;
 
 use PHPUnit\Framework\TestCase;
 use Symfony\Component\HttpFoundation\Request;
+use Symfony\Component\HttpFoundation\Session\SessionInterface;
 use Symfony\Component\HttpKernel\Exception\BadRequestHttpException;
 use Symfony\Component\Security\Core\Exception\BadCredentialsException;
 use Symfony\Component\Security\Core\Security;
@@ -165,7 +166,7 @@ class FormLoginAuthenticatorTest extends TestCase
 
     private function createSession()
     {
-        return $this->createMock('Symfony\Component\HttpFoundation\Session\SessionInterface');
+        return $this->createMock(SessionInterface::class);
     }
 }
 

src/Symfony/Component/Security/Http/Tests/Firewall/LogoutListenerTest.php

@@ -19,6 +19,7 @@ use Symfony\Component\HttpFoundation\Response;
 use Symfony\Component\HttpKernel\Event\RequestEvent;
 use Symfony\Component\Security\Http\Event\LogoutEvent;
 use Symfony\Component\Security\Http\Firewall\LogoutListener;
+use Symfony\Component\Security\Http\Logout\LogoutHandlerInterface;
 use Symfony\Component\Security\Http\Logout\LogoutSuccessHandlerInterface;
 
 class LogoutListenerTest extends TestCase
@@ -183,7 +184,7 @@ class LogoutListenerTest extends TestCase
         $response = new Response();
         $logoutSuccessHandler->expects($this->any())->method('onLogoutSuccess')->willReturn($response);
 
-        $handler = $this->createMock('Symfony\Component\Security\Http\Logout\LogoutHandlerInterface');
+        $handler = $this->createMock(LogoutHandlerInterface::class);
         $handler->expects($this->once())->method('logout')->with($request, $response, $token);
         $listener->addHandler($handler);