minor #16186 [2.7][tests] Use @requires annotation when possible (nicolas-grekas)

This PR was merged into the 2.7 branch.

Discussion
----------

[2.7][tests] Use @requires annotation when possible

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

Commits
-------

b028aea [tests] Use @requires annotation when possible

Author: nicolas-grekas

Tests/DataCollectorTranslatorTest.php

@@ -17,12 +17,6 @@
 
 class DataCollectorTranslatorTest extends \PHPUnit_Framework_TestCase
 {
-    protected function setUp()
-    {
-        if (!class_exists('Symfony\Component\HttpKernel\DataCollector\DataCollector')) {
-            $this->markTestSkipped('The "DataCollector" is not available');
-        }
-    }
     public function testCollectMessages()
     {
         $collector = $this->createCollector();

Tests/Loader/JsonFileLoaderTest.php

@@ -16,13 +16,6 @@
 
 class JsonFileLoaderTest extends \PHPUnit_Framework_TestCase
 {
-    protected function setUp()
-    {
-        if (!class_exists('Symfony\Component\Config\Loader\Loader')) {
-            $this->markTestSkipped('The "Config" component is not available');
-        }
-    }
-
     public function testLoad()
     {
         $loader = new JsonFileLoader();

Tests/LoggingTranslatorTest.php

@@ -17,13 +17,6 @@
 
 class LoggingTranslatorTest extends \PHPUnit_Framework_TestCase
 {
-    protected function setUp()
-    {
-        if (!interface_exists('Psr\Log\LoggerInterface')) {
-            $this->markTestSkipped('The "LoggerInterface" is not available');
-        }
-    }
-
     public function testTransWithNoTranslationIsLogged()
     {
         $logger = $this->getMock('Psr\Log\LoggerInterface');