[TASK] Code-cleanup for ContentObjectRenderer

Change-Id: I854edf2cf3d92236a9873bb37e3fef28ce6dc242
Resolves: #71690
Releases: master
Reviewed-on: https://review.typo3.org/44800


Reviewed-by: Stefan Neufeind <typo3.neufeind@speedpartner.de>
Tested-by: Stefan Neufeind <typo3.neufeind@speedpartner.de>
Reviewed-by: Adrian von Arx <av@qmailr.ch>
Tested-by: Adrian von Arx <av@qmailr.ch>
Reviewed-by: Markus Klein <markus.klein@typo3.org>
Tested-by: Markus Klein <markus.klein@typo3.org>