[BUGFIX] DebuggerUtility should return css when requested.

The DebuggerUtility of Extbase should only echo the CSS when
the debug info is echoed as well, otherwise it should be
returned just like the option describes it.

Resolves: #60893
Releases: master
Change-Id: I7196df201cb5974308aaf103aac5d63e63c02e61
Reviewed-on: https://review.typo3.org/45147


Reviewed-by: Wouter Wolters <typo3@wouterwolters.nl>
Reviewed-by: Markus Klein <markus.klein@typo3.org>
Reviewed-by: Frank Nägler <frank.naegler@typo3.org>
Tested-by: Frank Nägler <frank.naegler@typo3.org>
Reviewed-by: Jigal van Hemert <jigal.van.hemert@typo3.org>
Tested-by: Jigal van Hemert <jigal.van.hemert@typo3.org>