[TASK] Remove namespace declaration in ContentSecurityPolicies.php

There is no point in having namespace declarations
in those config files.

Releases: main
Resolves: #101944
Change-Id: Iccb97731a1e66a45c12d69c01f85def74073f0cc
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/81077


Tested-by: Oliver Klee <typo3-coding@oliverklee.de>
Tested-by: core-ci <typo3@b13.com>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>
Reviewed-by: Oliver Klee <typo3-coding@oliverklee.de>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>