Partial Revert "[FIX] sale: subtotal computation and display"

This partially reverts commit e2e27b41.

The commit changes the DOM structure in order to pretty print both
amount (value without tax, B2B setting) and total price (value with tax,
B2C setting). Actually having both (B2B and B2C) is a client
misconfiguration and we do not support that, furthermore changing the DOM
structures can break inherited templates.

The said commit was also fine tunning 716ff76d, the fine tune is
related the the removal of the dynamic colspan attribute. The section,
note and subtotal should take the entire width of the table, setting the
colspan to an abritary maximum ensures they fill the entire width.

closes odoo/odoo#32194

Signed-off-by: Jérémy Kersten (jke) <jke@openerp.com>