[BUGFIX] Populate extension configuration on install

Instead of duplicating default extension configuration
in DefaultConfiguration.php, we now populate it
after LocalConfiguration.php has been written.

Benefit is that we don't duplicate configuration and
that we even can have other system extensions enabled
by default without having to touch anything.

Resolves: #83420
Releases: master
Change-Id: I4118066e986bc7bab2dcb0cc67dbd4a2d89c70a3
Reviewed-on: https://review.typo3.org/55209


Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>
Reviewed-by: Wouter Wolters <typo3@wouterwolters.nl>
Reviewed-by: Stefan Neufeind <typo3.neufeind@speedpartner.de>
Reviewed-by: Helmut Hummel <typo3@helhum.io>
Tested-by: Helmut Hummel <typo3@helhum.io>