[FIX] l10n_za: tax report missing 15A

The missing 15A tax report line was added in odoo/odoo#90369 but it was not included in the VAT Payable/ Refundable Total line.
With this commit, we add codes to TotalA and TotalB and modify the final total to use these codes instead.

Bug report directly to me

closes odoo/odoo#122979

X-original-commit: 897024c097f117c130ce83502bca24f940a083fd
Signed-off-by: John Laterre (jol) <jol@odoo.com>
Signed-off-by: Ayob Habib (ayh) <ayh@odoo.com>

addons/l10n_za/data/account_tax_report_data.xml

@@ -15,10 +15,11 @@
         <field name="line_ids">
             <record id="total_vat_payable" model="account.report.line">
                 <field name="name">[20] VAT PAYABLE/REFUNDABLE (Total A - Total B)</field>
-                <field name="aggregation_formula">(VAT4.balance + VAT4A.balance + (SEC6.balance * 0.6 + SEC7.balance) + VAT11.balance + VAT12.balance) - (VAT14.balance + VAT14A.balance + VAT15.balance + VAT16.balance + VAT17.balance + VAT18.balance)</field>
+                <field name="aggregation_formula">TotalA.balance - TotalB.balance</field>
                 <field name="children_ids">
                     <record id="total_output_tax" model="account.report.line">
                         <field name="name">[13] Total A: TOTAL OUTPUT TAX (4 + 4A + 9 + 11 + 12)</field>
+                        <field name="code">TotalA</field>
                         <field name="aggregation_formula">VAT4.balance + VAT4A.balance + (SEC6.balance * 0.6 + SEC7.balance) + VAT11.balance + VAT12.balance</field>
                         <field name="children_ids">
                             <record id="standard_rate_exclude_capital_goods_service" model="account.report.line">
@@ -199,6 +200,7 @@
                     </record>
                     <record id="total_input_tax" model="account.report.line">
                         <field name="name">[19] Total B: TOTAL INPUT TAX (14 + 14A + 15 + 15A + 16 + 17 + 18)</field>
+                        <field name="code">TotalB</field>
                         <field name="aggregation_formula">VAT14.balance + VAT14A.balance + VAT15.balance + VAT15A.balance + VAT16.balance + VAT17.balance + VAT18.balance</field>
                         <field name="children_ids">
                             <record id="capital_goods_services_supplied" model="account.report.line">