The 'inset' checkbox of the shadow option was still displayed for no
reason. A "display: none" inline style was added on it but as inline
style is not considered for editor widgets I don't know how it could
have ever worked.

closes odoo/odoo#54168

X-original-commit: b0de225c721e54b76dcbe49f9769ac371db39c05
Signed-off-by: Quentin Smetz (qsm) <qsm@odoo.com>