[TASK] Clean up DH->copyL10nOverlayRecords()

* Set this internal method to protected
* Add type hints for two arguments that are safe to set
* Skip BU::isTableLocalizable(), and check state of the
  two main TCA 'ctrl' props with an early return instead
* add @todo for incomplete use of getTSconfig_pidValue() results
* $this->BE_USER->workspace is always an int, skip cast
* fetchAllAssociative() always returns an array, remove
  an if and return early with empty result set instead

Resolves: #103912
Related: #103828
Releases: main
Change-Id: I3d11822c40c0c58474225ba95ff86c5b672c9f7c
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/84397


Tested-by: core-ci <typo3@b13.com>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>
Reviewed-by: Anja Leichsenring <aleichsenring@ab-softlab.de>
Reviewed-by: Stefan Bürk <stefan@buerk.tech>
Tested-by: Anja Leichsenring <aleichsenring@ab-softlab.de>
Tested-by: Stefan Bürk <stefan@buerk.tech>