[FIX]: point_of_sale: terms and conditions added in invoice

When the option that set default terms and conditions is set in the
invoice setting, it is not taken into account on invoices created from
the point of sale.

We are now set the default terms and conditions on the invoices created
from the POS.

closes odoo/odoo#75016

Signed-off-by: pimodoo <pimodoo@users.noreply.github.com>