[IMP] l10n_es: Establish more appropriate cash_difference accounts

Use 778000 and 678000 accounts for default_cash_difference_income_account_id and default_cash_difference_expense_account_id
Use 431200 and 411000 for account_journal_payment_debit and account_journal_payment_credit
Fix length for transfer_account_code_prefix

closes odoo/odoo#105519

Signed-off-by: Olivier Colson (oco) <oco@odoo.com>