[BUGFIX] Always call GU::intExplode with a string in EXT:extbase

This helps avoid breakage when GeneralUtility will switch to
strict mode.

This change also prevents a whole bunch of possible invalid
array access warnings.

Resolves: #97583
Relates: #97578
Releases: main
Change-Id: Id500872d91a7b47c647bb9a4d860477ee9ca7595
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/74961


Tested-by: core-ci <typo3@b13.com>
Tested-by: Georg Ringer <georg.ringer@gmail.com>
Tested-by: Stefan Bürk <stefan@buerk.tech>
Reviewed-by: Georg Ringer <georg.ringer@gmail.com>
Reviewed-by: Stefan Bürk <stefan@buerk.tech>