[TASK] Use str_contains instead of strpos where possible

The (ugly) statement strpos($haystack, 'needle') !== false can be safely
replaced with str_contains($haystack, 'needle'). This is possible, as
a symfony polyfill for php 8.0 functions is in place.

Resolves: #95466
Releases: master
Change-Id: I313f47832a254c23c6815b6b44557a01019e59e7
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/71429


Tested-by: core-ci <typo3@b13.com>
Tested-by: Simon Schaufelberger <simonschaufi+typo3@gmail.com>
Tested-by: Benni Mack <benni@typo3.org>
Reviewed-by: Simon Schaufelberger <simonschaufi+typo3@gmail.com>
Reviewed-by: Wouter Wolters <typo3@wouterwolters.nl>
Reviewed-by: Benni Mack <benni@typo3.org>