[TASK] Cleanup ContentObject\ContentObjectRenderer

Implement early return for many methods.

Change-Id: I7e0c8549037f4ab15ee8653d124891bad655db83
Resolves: #54823
Releases: 6.2
Reviewed-on: https://review.typo3.org/26687
Reviewed-by: Oliver Klee
Reviewed-by: Markus Klein
Tested-by: Markus Klein
Reviewed-by: Wouter Wolters
Tested-by: Wouter Wolters