The uom must be displayed to the customer in any case.
Otherwise portal user couldn't sign their online quote if
they couldn't read the uom (ex: a contract of one year or one day)

Fine tuning of https://github.com/odoo/odoo/commit/342dd5ffb8281cb5c37fea4fb96db2b570c30122



opw:2411108

closes odoo/odoo#65010

Signed-off-by: Simon Goffin (sig) <sig@openerp.com>