[FIX] account: avoid base being included twice in group

Create multiple tax and assign them to the same tax group.
Create an invoice, with two lines, each one with one tax of the group.
Save and click on "Preview" or print invoice.

The tax group will be reported applied on just the first line
This append because of 4d62a94a.
Reverting commit to restore the former behavior in which the tax base
amount is added for every line in which the tax group component is
found. While this other behavior could be an issue for some user the
behavior is more consistent accounting-wise and the template could easily
be changed to adapt to user needs.

opw-2170069

closes odoo/odoo#43254

Signed-off-by: Nicolas Martinelli (nim) <nim@odoo.com>