minor #30427 [PropertyInfo] Removes useless namespace (tsantos84)

This PR was merged into the 4.3-dev branch.

Discussion
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[PropertyInfo] Removes useless namespace

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

Removes a duplicated namespace in test file. The target branch is `master` because [this feature](f6510cda40) was not released yet.

Commits
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b3d536f04d [PropertyInfo] Removed useless namespace

src/Symfony/Component/PropertyInfo/Tests/Fixtures/DefaultValue.php

@@ -1,7 +1,5 @@
 <?php
 
-namespace Symfony\Component\PropertyInfo\Tests\Fixtures;
-
 /*
  * This file is part of the Symfony package.
  *