[TASK] Remove unnecessary pageTS config of HtmlArea

HTMLarea defines htmlSpecialChars=0 which is set by default.
If it is overriden by an installation, this can still be done and
does not break anything then.

Resolves: #79268
Releases: master
Change-Id: I39022320d3f4834ceea4a52e3a4e80cd34b90506
Reviewed-on: https://review.typo3.org/51260


Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Wouter Wolters <typo3@wouterwolters.nl>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>
Reviewed-by: Anja Leichsenring <aleichsenring@ab-softlab.de>
Tested-by: Anja Leichsenring <aleichsenring@ab-softlab.de>