[BUGFIX] Class 'TYPO3\CMS\Recordlist\Browser\GeneralUtility' not found

Fixing regression from issue #54995 and use
namespaced class name in TYPO3_6-1 branch.

Fixes: #55246
Releases: 6.1
Change-Id: I0f98de7664a81ba72262e8f85e690240d53c9c23
Reviewed-on: https://review.typo3.org/26994
Reviewed-by: Oliver Hader
Tested-by: Oliver Hader