Correct document for embedded PDF (#29667)

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#### Summary <!-- Provide a general summary of your changes -->
This pull request updates how `SalesHeader` is populated in the `Export
XRechnung Document` codeunit. Instead of using the
`PEPPOLMgt.FindNextSalesInvoiceRec` and
`PEPPOLMgt.FindNextSalesCreditMemoRec` methods, it now uses
`TransferFields` and explicitly sets the `"Document Type"` field. This
change fixes the wrong document selection for both invoices and credit
memos.


#### Work Item(s) <!-- Add the issue number here after the #. The issue
needs to be open and approved. Submitting PRs with no linked issues or
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Fixes #29665

[AB#620565](https://dynamicssmb2.visualstudio.com/1fcb79e7-ab07-432a-a3c6-6cf5a88ba4a5/_workitems/edit/620565)

Author: miljance

Apps/DE/EDocumentDE/app/src/XRechnung/ExportXRechnungDocument.Codeunit.al

@@ -956,12 +956,14 @@ codeunit 13916 "Export XRechnung Document"
             Database::"Sales Invoice Header":
                 begin
                     HeaderRecordRef.SetTable(SalesInvoiceHeader);
-                    PEPPOLMgt.FindNextSalesInvoiceRec(SalesInvoiceHeader, SalesHeader, 1);
+                    SalesHeader.TransferFields(SalesInvoiceHeader);
+                    SalesHeader."Document Type" := SalesHeader."Document Type"::Invoice;
                 end;
             Database::"Sales Cr.Memo Header":
                 begin
                     HeaderRecordRef.SetTable(SalesCrMemoHeader);
-                    PEPPOLMgt.FindNextSalesCreditMemoRec(SalesCrMemoHeader, SalesHeader, 1);
+                    SalesHeader.TransferFields(SalesCrMemoHeader);
+                    SalesHeader."Document Type" := SalesHeader."Document Type"::"Credit Memo";
                 end;
         end;
         PEPPOLMgt.GeneratePDFAttachmentAsAdditionalDocRef(