CLONE 2019R3 - SO Export - suppress DistributorInvoiceNumber element when no data is present

The <DistributorInvoiceNumber/> element is being included in the Suggested Order Export when there is no data present, in these scenarios the element should be suppressed, as we do with other elements in this export.

Per AC in CFAMX-3942:

1. Confirm that the Suggested Order Export does NOT include the new element (DistributorInvoiceNumber) when the order is Created
   • There is no ASN associated to the order at this time
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6. Confirm that the Suggested Order Export does NOT include the new element (DistributorInvoiceNumber) when the order is Received and an ASN has NOT been associated to the order
7. Confirm that the Suggested Order Export does NOT include the new element (DistributorInvoiceNumber) the order is changed thru the Correct Receive process and an ASN has NOT been associated to the order
8. Confirm that the Suggested Order Export does NOT include the new element (DistributorInvoiceNumber)when the order is changed thru the Change Apply Date process and an ASN has NOT been associated to the order
9. Confirm that the Suggested Order Export does NOT include the new element (DistributorInvoiceNumber) when the order is Cancelled and an ASN has NOT been associated to the order