[16.0][FIX] account_financial_report: take multiple account tags per tax into account

[dhx]

• When there are multiple repartition lines having different tax tags the VAT report will take all the tax lines for all tags into consideration leading to wrong results (e.g.: l10n_at.account_tax_template_sales_rev_charge_0_code021_1e)
• This patch will fix this by only using the balance of account move lines for the linked tax tags.
• As this change leads to the account move line balance being only taken into account for the tags being explicitly set in the repartition line the net sum will not be affected when the tag is not associated to the base repartition line (leading to changes in the expected behaviour in test_01_compute).