[TASK] Use constant 'TYPO3' in global script files

Avoid usage of constant 'TYPO3_MODE' as security gate
in script files that don't run in class or callable context.
Use new constant 'TYPO3' instead.

Resolves: #92949
Related: #92947
Related: #92948
Releases: master
Change-Id: I95618793ed29b4b71e9e97ea8da124924d6753fc
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/66938


Tested-by: TYPO3com <noreply@typo3.com>
Tested-by: Daniel Haupt <mail@danielhaupt.de>
Tested-by: Anja Leichsenring <aleichsenring@ab-softlab.de>
Reviewed-by: Daniel Haupt <mail@danielhaupt.de>
Reviewed-by: Anja Leichsenring <aleichsenring@ab-softlab.de>