minor #30364 [FrameworkBundle] Removed eval() from KernelShutdownOnTearDownTrait (skalpa)

This PR was merged into the 4.2 branch.

Discussion
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[FrameworkBundle] Removed eval() from KernelShutdownOnTearDownTrait

| Q             | A
| ------------- | ---
| Branch?       | 4.2
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| License       | MIT

Apart from triggering the #30362 bug, the `eval()` block from #30124 also broke my workflow: static code analyzers don't like this, and the trait even crashes PHPStan.

It may also bring up other compatibility issues to other people (ie: I know companies that completely disable `eval()` on their servers).

As it was only required to keep the trait compatible with PHP 5.x, it is unnecessary on 4.x that requires PHP 7.1+, and this PR removes it on the 4.2 branch.

Commits
-------

324b70afa3 Removed eval() from KernelShutdownOnTearDownTrait

src/Symfony/Bundle/FrameworkBundle/Test/KernelShutdownOnTearDownTrait.php

@@ -16,9 +16,6 @@ use PHPUnit\Framework\TestCase;
 // Auto-adapt to PHPUnit 8 that added a `void` return-type to the tearDown method
 
 if (method_exists(\ReflectionMethod::class, 'hasReturnType') && (new \ReflectionMethod(TestCase::class, 'tearDown'))->hasReturnType()) {
-    eval('
-    namespace Symfony\Bundle\FrameworkBundle\Test;
-
     /**
      * @internal
      */
@@ -29,7 +26,6 @@ if (method_exists(\ReflectionMethod::class, 'hasReturnType') && (new \Reflection
             static::ensureKernelShutdown();
         }
     }
-');
 } else {
     /**
      * @internal