[!!!][TASK] Remove old typoscript constants "TSConstantEditor"

Remove support for the special constant "TSConstantEditor".
This constant was used to show additional helping information
in the constants editor and is dropped as ancient and widely
unknown and rarely used feature.

Releases: master
Resolves: #82398
Change-Id: I9825ca5a321c6c92159a5cd94ca5ed6c9ea1d0ff
Reviewed-on: https://review.typo3.org/54048


Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>
Reviewed-by: Markus Hölzle <typo3@markus-hoelzle.de>
Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Benni Mack <benni@typo3.org>
Tested-by: Benni Mack <benni@typo3.org>