[BUGFIX] Do not override disabled user settings

When the realName or email field of a user is disabled
by TSconfig, the current values will remain when saving.

Resolves: #94075
Releases: master, 10.4
Change-Id: Idfa4ba9f0d558575b9d3fcccd33784513e54d016
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/69053


Tested-by: core-ci <typo3@b13.com>
Tested-by: Oliver Bartsch <bo@cedev.de>
Tested-by: Richard Haeser <richard@richardhaeser.com>
Reviewed-by: Oliver Bartsch <bo@cedev.de>
Reviewed-by: Richard Haeser <richard@richardhaeser.com>