fix: ensure SellingController.onload gets called for SO & DN

(cherry picked from commit 8431e3c275)

erpnext/selling/doctype/sales_order/sales_order.py

@@ -185,6 +185,8 @@ class SalesOrder(SellingController):
 		super().__init__(*args, **kwargs)
 
 	def onload(self) -> None:
+		super().onload()
+
 		if frappe.db.get_single_value("Stock Settings", "enable_stock_reservation"):
 			if self.has_unreserved_stock():
 				self.set_onload("has_unreserved_stock", True)

erpnext/stock/doctype/delivery_note/delivery_note.py

@@ -208,6 +208,8 @@ class DeliveryNote(SellingController):
 			)
 
 	def onload(self):
+		super().onload()
+
 		if self.docstatus == 0:
 			self.set_onload("has_unpacked_items", self.has_unpacked_items())