[FIX] account: process_reconciliations @api.v7
[FIX] account: process_reconciliations @api.v7

The method `process_reconciliations` is written in api.v7.
Therefore, any calls done on ORM models must be done
in the 7.0 API in this method.

To reproduce the issue:
 - Open a pos session, and sell something, select a partner
   and choose to create an invoice.
 - Come back to the back-end, and in the accounting dashboard,
   in Customer Invoices > More > Matching payment,
   hit ctrl-enter to reconcile all the balanced items in the sheet.

opw-654410

stephen144/odoo,microcom/odoo,laslabs/odoo,stephen144/odoo,stephen144/odoo,dfang/odoo,hip-odoo/odoo,sysadminmatmoz/OCB,sysadminmatmoz/OCB,sysadminmatmoz/OCB,laslabs/odoo,ygol/odoo,hip-odoo/odoo,laslabs/odoo,laslabs/odoo,dfang/odoo,bplancher/odoo,hip-odoo/odoo,hip-odoo/odoo,optima-ict/odoo,optima-ict/odoo,storm-computers/odoo,optima-ict/odoo,storm-computers/odoo,ygol/odoo,sysadminmatmoz/OCB,microcom/odoo,dfang/odoo,Elico-Corp/odoo_OCB,stephen144/odoo,storm-computers/odoo,ygol/odoo,optima-ict/odoo,dfang/odoo,sysadminmatmoz/OCB,sysadminmatmoz/OCB,bplancher/odoo,bplancher/odoo,microcom/odoo,Elico-Corp/odoo_OCB,Elico-Corp/odoo_OCB,dfang/odoo,storm-computers/odoo,Elico-Corp/odoo_OCB,bplancher/odoo,hip-odoo/odoo,microcom/odoo,storm-computers/odoo,storm-computers/odoo,laslabs/odoo,ygol/odoo,sysadminmatmoz/OCB,ygol/odoo,optima-ict/odoo,stephen144/odoo,ygol/odoo,Elico-Corp/odoo_OCB,microcom/odoo,Elico-Corp/odoo_OCB,laslabs/odoo,ygol/odoo,dfang/odoo,stephen144/odoo,hip-odoo/odoo,microcom/odoo,optima-ict/odoo,bplancher/odoo,bplancher/odoo