[TASK] Do not use constants in low-level classes

There are certain PHP classes used in the testing framework that
use constants like "LF" which are defined by the SystemEnvironmentBuilder.

The testing framework depends on these classes, but should not
depend on global constants like "LF". The patch changes the lines to "\n"
allowing to continue slimming down testing framework.

Resolves: #89712
Releases: master, 9.5
Change-Id: Ieace867d13ab320a3273e1119a3a2ecc9268103b
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/62345


Reviewed-by: Oliver Klee <typo3-coding@oliverklee.de>
Reviewed-by: Alexander Schnitzler <review.typo3.org@alexanderschnitzler.de>
Reviewed-by: Benni Mack <benni@typo3.org>
Reviewed-by: Susanne Moog <look@susi.dev>
Tested-by: TYPO3com <noreply@typo3.com>
Tested-by: Alexander Schnitzler <review.typo3.org@alexanderschnitzler.de>
Tested-by: Benni Mack <benni@typo3.org>
Tested-by: Susanne Moog <look@susi.dev>