[TASK] Cleanup ArrayUtility::sortArraysByKey()

Replace strtolower and ternary operations with strcasecmp.

Change-Id: Ia962ef879c6ba1d91081db78f74fc577fa67c467
Resolves: #55899
Releases: 6.2
Reviewed-on: https://review.typo3.org/27559
Reviewed-by: Oliver Klee
Reviewed-by: Christian Kuhn
Tested-by: Christian Kuhn
Reviewed-by: Wouter Wolters
Tested-by: Wouter Wolters