[BUGFIX] Do not show disabled checkbox

Revert a style change, added in #95325, which
led to disabled checkboxes are being shown, while
only their label should be visible. Those checkbox
classes hide the actual checkbox, while the label
acts as one. This allows extended styling, e.g.
"icon checkboxes" or "toggle checkboxes".

Instead add the disabled style to the correct
checkbox component, which is acutally using the
checkbox element and no label.

Resolves: #95325
Releases: master
Change-Id: I0842c184e629a3c4327c18db92affde58c32924d
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/71213


Tested-by: core-ci <typo3@b13.com>
Tested-by: Wouter Wolters <typo3@wouterwolters.nl>
Tested-by: Benni Mack <benni@typo3.org>
Reviewed-by: Wouter Wolters <typo3@wouterwolters.nl>
Reviewed-by: Benni Mack <benni@typo3.org>