[FIX] account: qr_code_urls bug in report invoice template

To reproduce:

1) activate qr code on invoices
2) print an invoice with a qr code
3) print a followup letter, and attach the printed invoice

-> error due to missing 'qr_code_urls' variable in invoice template

This can happen with any report calling this template, thus we decided to set the qr_code_urls
inside the `report_invoice_document` template directly, so we never need to set it again in _get_report_values()
This allows to remove the following report classes (done in master due to stable policy)
- `ReportInvoiceWithoutPayment`
- `ReportInvoiceWithPayment`
- `PosInvoiceReport` (not even used anywhere)

closes odoo/odoo#106605

X-original-commit: a87460bdb82b7b2ab88f397f3506d0f380d86cfd
Signed-off-by: Brice Bartoletti (bib) <bib@odoo.com>

addons/account/views/report_invoice.xml

@@ -246,9 +246,10 @@
                         <strong>Incoterm: </strong><span t-field="o.invoice_incoterm_id.code"/> - <span t-field="o.invoice_incoterm_id.name"/>
                     </p>
                     <div id="qrcode" t-if="o.display_qr_code and o.amount_residual > 0">
-                        <p t-if="qr_code_urls.get(o.id)">
+                        <t t-set="qr_code_url" t-value="o._generate_qr_code()"/>
+                        <p t-if="qr_code_url">
                             <strong class="text-center">Scan me with your banking app.</strong><br/><br/>
-                            <img class="border border-dark rounded" t-att-src="qr_code_urls[o.id]"/>
+                            <img class="border border-dark rounded" t-att-src="qr_code_url"/>
                         </p>
                     </div>
                 </div>