[TASK] Followup: Clean up composer.json of fixture extension

Remove unnecessary bloat from the composer.json

Releases: master
Resolves: #96102
Change-Id: Id5353c509ec2af23baae555f63cd3f123403364e
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/72332


Tested-by: Stefan Bürk <stefan@buerk.tech>
Tested-by: core-ci <typo3@b13.com>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>
Reviewed-by: Stefan Bürk <stefan@buerk.tech>
Reviewed-by: Oliver Klee <typo3-coding@oliverklee.de>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>