The servicing_instruction column was not mapped in
Koha::Acquisition::Order->to_api_mapping, so it was exposed verbatim in
the REST API order representation. Since api/v1/swagger/definitions/order.yaml
does not declare this property and sets additionalProperties: false, any
request touching the acquisitions/orders endpoint (e.g. the "Receive
shipments" page) failed with a 500 error: "Properties not allowed:
servicing_instruction".
Exclude it from the API representation, consistent with the other
EDIFACT-only columns (line_item_id, suppliers_reference_number, etc.)
that are already excluded the same way.
Test plan:
1) Go to a vendor page, create a basket, add an order line, and close
the basket.
2) From the vendor page, click "Receive shipments".
3) Without this patch, the orders table fails to load with a 500 error
mentioning "Properties not allowed: servicing_instruction".
4) With this patch applied, the orders table loads correctly.
5) prove t/db_dependent/api/v1/acquisitions_orders.t
Signed-off-by: Pedro Amorim <pedro.amorim@openfifth.co.uk>