[TASK] Remove unused code in ContentObjectRenderer

The ContentObjectRenderer throws a warning under certain
circumstances in PHP8. The warning is generated by code,
which is unused.

This patch removes the unused code in ContentObjectRenderer.

Resolves: #95921
Releases: master, 11.5
Change-Id: Ifb6f3557434626ec71f37d92181a5b156f6b39e3
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/72272


Tested-by: core-ci <typo3@b13.com>
Tested-by: Benni Mack <benni@typo3.org>
Tested-by: Oliver Bartsch <bo@cedev.de>
Reviewed-by: Oliver Klee <typo3-coding@oliverklee.de>
Reviewed-by: Benni Mack <benni@typo3.org>
Reviewed-by: Oliver Bartsch <bo@cedev.de>