[TASK] DatabaseRecordList Drop `getVisibleColumns()`

After the removal of TCA [ctrl][thumbnails] in #92118, the method
'getVisibleColumns()' isn't used any more. Therefore, it has been
removed.

Releases: master
Resolves: #92226
Change-Id: Iff0ad528e96a0f89fc1f59d9728d9a96374f793f
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/65629


Tested-by: TYPO3com <noreply@typo3.com>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Andreas Fernandez <a.fernandez@scripting-base.de>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Reviewed-by: Oliver Klee <typo3-coding@oliverklee.de>
Reviewed-by: Andreas Fernandez <a.fernandez@scripting-base.de>