[TASK] Resolve unit test failures under PHP 8.1

libsodium doesn't support multi-threading. It's unclear why
this code didn't fail previously on 8.0, but sending a thread
count to password_hash() while ext/sodium is enabled is not
supported regardless. I believe this is the least-invasive
fix.

Resolves: #95159
Releases: master
Change-Id: I0e46ad46bc1440efcc118abd9d1dd82e9de4d2b1
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/70975


Tested-by: core-ci <typo3@b13.com>
Tested-by: Jochen <rothjochen@gmail.com>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>
Reviewed-by: Oliver Klee <typo3-coding@oliverklee.de>
Reviewed-by: Jochen <rothjochen@gmail.com>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>