[BUGFIX] Resolve a stray strpos call

This conversion got past the big conversion patch
before, probably due to the negation.

Resolves: #97640
Releases: main, 11.5
Change-Id: I67dd19c286ce25ad8cda71c1451fa84ed25dc971
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/74784


Tested-by: core-ci <typo3@b13.com>
Tested-by: Stefan Bürk <stefan@buerk.tech>
Reviewed-by: Stefan Bürk <stefan@buerk.tech>