[FIX] sale_management: SO company change should not reset all lines

unless there is another template to apply by default

closes odoo/odoo#86899

Task-id: 2798588
Signed-off-by: Yannick Tivisse (yti) <yti@odoo.com>
Signed-off-by: Victor Feyens (vfe) <vfe@odoo.com>