[BUGFIX] Store extension configuration in key EXTENSIONS

The previous patch changed it to EXTCONF,
but this conflicts with other stuff.

Resolves: #82370
Releases: master
Change-Id: Ib515a1364f45739fb7f8e0fa3e781099f1c1a107
Reviewed-on: https://review.typo3.org/53999


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