Issue #3316855: Remove \Drupal\Tests\package_manager\Kernel\PackageManagerKernelTestBase::copyFixtureFolderToStageDirectoryOnApply()
requested to merge issue/automatic_updates-3316855:3316855-remove-drupaltestspackagemanagerkernelpackagemanagerkerneltestbasecopyfixturefoldertostagedirectoryonapply into 8.x-2.x