docs(microflow-example): make M029 a genuine memory retrieve (owner default)

M029_RetrieveByAssociation is labelled "RETRIEVE by association … instead of
database XPath", but its Order_Customer association was owner="both", so a
reverse retrieve consumed as a list resolves to a database retrieve (Mendix
returns a single object for a reverse owner-both Reference — see #726). That
made the example contradict its own description.

Switch Order_Customer to owner="default" so the reverse retrieve stays an
in-memory AssociationRetrieveSource returning a list, matching the label. The
other users of the association (M018/M019/M032) navigate/set from the Order
owner side, so default ownership is fine. Full doctype re-checks at 0 errors.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: ako

mdl-examples/doctype-tests/02-microflow-examples.mdl

@@ -95,10 +95,14 @@ create non-persistent entity MfTest.ImportRow (
 );
 
 -- Create associations
+-- Order_Customer is owner="default" so a reverse retrieve-by-association from
+-- the Customer side (M029) stays an in-memory AssociationRetrieveSource that
+-- returns a list. (A reverse Reference over an owner="both" association resolves
+-- to a single object in Mendix, forcing a database retrieve instead — see #726.)
 create association MfTest.Order_Customer
 from MfTest.Order to MfTest.Customer
 type reference
-owner both;
+owner default;
 
 create association MfTest.Order_Product
 from MfTest.Order to MfTest.Product