Fix comment about obsolete type user with dbType json.

Resolves: #102832
Releases: main, 12.4
Change-Id: I390a1a7d3a7fe4d511f361efae4c2735f9b34c4a
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/82453


Tested-by: core-ci <typo3@b13.com>
Reviewed-by: Anja Leichsenring <aleichsenring@ab-softlab.de>
Tested-by: Anja Leichsenring <aleichsenring@ab-softlab.de>