bug #30245 fix lost namespace in eval (fizzka)

This PR was squashed before being merged into the 4.2 branch (closes #30245).

Discussion
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fix lost namespace in eval

Bugfix:
phpunit8 tearDown() declaration

Commits
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8743a1ada8 fix lost namespace in eval

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

@@ -16,7 +16,9 @@ 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('
+    eval('
+    namespace Symfony\Bundle\FrameworkBundle\Test;
+
     /**
      * @internal
      */