[TASK] Avoid withConsecutive() in SlugHelperTest

Resolves: #100442
Related: #100249
Releases: main
Change-Id: I5b9c5f90d2a7688f5808513df618219b4eb14bf4
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/78454


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