[BUGFIX] Prevent undefined array key in ext lowlevel

There are several checks related to array key
'_CURRENT_VERSION' on versioned records. Since
PHP 8 those checks are not safe anymore and
can result in errors.

Releases: main, 11.5
Resolves: #100336
Change-Id: I8b5a956a987a3d8c9690e824e0fccfd6570e0069
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/78306


Tested-by: core-ci <typo3@b13.com>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>