[REV] account: commit 2f6a35eb

2f6a35eb introduced the fact that when doing a full refund of an invoice, the same account was used as on the original invoice, instead of the one on the tax refund repartition lines, though the tags were still the refund ones. This is wrong.

Also, it restored an inconsistent data setup in a test, while the current version was actually correct.

Forward-port-of: https://github.com/odoo/odoo/pull/83837
Part-of: odoo/odoo#84246