[TASK] Discourage usage of $LANG->csConvObj and parserFactory

The csConvObj is decoupled from LanguageService and
not used directly anymore.

Any calls directly to the property csConvObj should be avoided
as was marked as deprecated.

Same goes with the property "parserFactory" of the
LanguageService class. The parser factory is not called
from the language object anymore and the property can be
removed.

Resolves: #73482
Releases: master
Change-Id: I94d7fca658c2b9e8cffc62f5bdb0c5ce83c894a2
Reviewed-on: https://review.typo3.org/46708


Reviewed-by: Wouter Wolters <typo3@wouterwolters.nl>
Tested-by: Wouter Wolters <typo3@wouterwolters.nl>
Reviewed-by: Georg Ringer <georg.ringer@gmail.com>
Tested-by: Georg Ringer <georg.ringer@gmail.com>