[TASK] Simplify a ContentObjectRendererTest detail

Some setUp() code is not triggered and thus obsolete.

Resolves: #104747
Releases: main
Change-Id: I72099d5d09bf36f83c381f3e12415a73e4190e56
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/85791


Reviewed-by: Stefan Bürk <stefan@buerk.tech>
Tested-by: Garvin Hicking <gh@faktor-e.de>
Tested-by: core-ci <typo3@b13.com>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Stefan Bürk <stefan@buerk.tech>
Reviewed-by: Garvin Hicking <gh@faktor-e.de>