minor #21686 Updated PHPUnit namespaces (peterrehm)

This PR was merged into the 3.2 branch.

Discussion
----------

Updated PHPUnit namespaces

| Q             | A
| ------------- | ---
| Branch?       | 3.2
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | -
| License       | MIT
| Doc PR        | -

Follow Up of #21663

Commits
-------

c2e80e3 Updated PHPUnit namespaces

Author: nicolas-grekas

Tests/Command/YamlLintCommandTest.php

@@ -11,6 +11,7 @@
 
 namespace Symfony\Bundle\FrameworkBundle\Tests\Command;
 
+use PHPUnit\Framework\TestCase;
 use Symfony\Bundle\FrameworkBundle\Command\YamlLintCommand;
 use Symfony\Bundle\FrameworkBundle\Console\Application;
 use Symfony\Component\Console\Application as BaseApplication;
@@ -25,7 +26,7 @@
  *
  * @author Robin Chalas <robin.chalas@gmail.com>
  */
-class YamlLintCommandTest extends \PHPUnit_Framework_TestCase
+class YamlLintCommandTest extends TestCase
 {
     private $files;
 

Tests/DependencyInjection/Compiler/CachePoolClearerPassTest.php

@@ -11,6 +11,7 @@
 
 namespace Symfony\Bundle\FrameworkBundle\Tests\DependencyInjection\Compiler;
 
+use PHPUnit\Framework\TestCase;
 use Symfony\Bundle\FrameworkBundle\DependencyInjection\Compiler\CachePoolClearerPass;
 use Symfony\Bundle\FrameworkBundle\DependencyInjection\Compiler\CachePoolPass;
 use Symfony\Component\DependencyInjection\Compiler\RemoveUnusedDefinitionsPass;
@@ -19,7 +20,7 @@
 use Symfony\Component\DependencyInjection\Definition;
 use Symfony\Component\DependencyInjection\Reference;
 
-class CachePoolClearerPassTest extends \PHPUnit_Framework_TestCase
+class CachePoolClearerPassTest extends TestCase
 {
     public function testPoolRefsAreWeak()
     {

Tests/DependencyInjection/Compiler/CachePoolPassTest.php

@@ -11,13 +11,14 @@
 
 namespace Symfony\Bundle\FrameworkBundle\Tests\DependencyInjection\Compiler;
 
+use PHPUnit\Framework\TestCase;
 use Symfony\Bundle\FrameworkBundle\DependencyInjection\Compiler\CachePoolPass;
 use Symfony\Component\DependencyInjection\ContainerBuilder;
 use Symfony\Component\DependencyInjection\Definition;
 use Symfony\Component\DependencyInjection\DefinitionDecorator;
 use Symfony\Component\DependencyInjection\Reference;
 
-class CachePoolPassTest extends \PHPUnit_Framework_TestCase
+class CachePoolPassTest extends TestCase
 {
     private $cachePoolPass;
 

Tests/DependencyInjection/Compiler/ControllerArgumentValueResolverPassTest.php

@@ -11,13 +11,14 @@
 
 namespace Symfony\Bundle\FrameworkBundle\Tests\DependencyInjection\Compiler;
 
+use PHPUnit\Framework\TestCase;
 use Symfony\Bundle\FrameworkBundle\DependencyInjection\Compiler\ControllerArgumentValueResolverPass;
 use Symfony\Component\DependencyInjection\ContainerBuilder;
 use Symfony\Component\DependencyInjection\Definition;
 use Symfony\Component\DependencyInjection\Reference;
 use Symfony\Component\HttpKernel\Controller\ArgumentResolver;
 
-class ControllerArgumentValueResolverPassTest extends \PHPUnit_Framework_TestCase
+class ControllerArgumentValueResolverPassTest extends TestCase
 {
     public function testServicesAreOrderedAccordingToPriority()
     {