Issue #3030359 by Mile23: FileSystemDeprecationTest in the wrong place since it's a kernel test

core/tests/Drupal/Tests/Core/File/FileSystemDeprecationTest.php → core/tests/Drupal/KernelTests/Core/File/FileSystemDeprecationTest.php

 <?php
 
-namespace Drupal\Tests\Core\File;
+namespace Drupal\KernelTests\Core\File;
 
 use Drupal\KernelTests\KernelTestBase;