[FIX] account: don't use CABA transition account when using a tax in reconciliation widget

Before, when using a cash basis tax in the bank reconciliation widget, the account chosen for the tax line corresponded to the tax transition account. This was wrong: since the entry is already reconciled, we want to use the actual repartition account, as nothing will move this amount from the transition account afterwards.

Indirectly linked to OPW 2865789

closes odoo/odoo#99465

X-original-commit: ff87397b
Signed-off-by: Laurent Smet <las@odoo.com>
Signed-off-by: Olivier Colson (oco) <oco@odoo.com>