[BUGFIX] Properly handle readOnly in BackendLayoutWizardElement

While the "readOnly" option is not supported as
columns config for renderType "belayoutwizard",
it might be automatically set by FormEngine in
case the field is defined with "l10n_display",
set to "defaultAsReadonly".

This is now properly handled.

Resolves: #96095
Related: #89152
Releases: main, 11.5
Change-Id: I2a5e3a96db66603d36633c72cf36407b21b90438
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/72413


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