[FIX] account: Fix tests depending the date after 18 months

Tests are crashing when the number of months between the data date and today is higher than 18 months due to the 'past_months_limit' field on account.reconcile.model.

closes odoo/odoo#67033

Signed-off-by: oco-odoo <oco-odoo@users.noreply.github.com>