[FIX] point_of_sale: right negation syntax in xml JS
[FIX] point_of_sale: right negation syntax in xml JS

f4bfc9075507e29296d25232461d8b85f9dbcd41 reverted a bunch of commits,
including a legit bugfix in a XML for JS templates

This commit re-does that bugfix

OPW 1895212

closes odoo/odoo#28062
ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo