[TASK] Extract simple mn attribute scenario from ext:irre_tutorial

The scenario provided by tables tx_irretutorial_mnattr_* gets
its own test extension and gets loaded where needed.

Resolves: #96459
Releases: main, 11.5
Change-Id: I48b08772f8c4d64f8a3ea930fc307a8d5d3f2189
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/72870


Tested-by: core-ci <typo3@b13.com>
Tested-by: Benni Mack <benni@typo3.org>
Tested-by: Stefan Bürk <stefan@buerk.tech>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>
Reviewed-by: Benni Mack <benni@typo3.org>
Reviewed-by: Stefan Bürk <stefan@buerk.tech>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>