fix: is_pos gets reset on making s_inv from s_ord (#20886)

* s_inv has is_pos default set as 1
diff --git a/erpnext/selling/doctype/sales_order/sales_order.py b/erpnext/selling/doctype/sales_order/sales_order.py
index e7cbf40..13d2b15 100755
--- a/erpnext/selling/doctype/sales_order/sales_order.py
+++ b/erpnext/selling/doctype/sales_order/sales_order.py
@@ -641,7 +641,6 @@
 			target.set_advances()
 
 	def set_missing_values(source, target):
-		target.is_pos = 0
 		target.ignore_pricing_rule = 1
 		target.flags.ignore_permissions = True
 		target.run_method("set_missing_values")
diff --git a/erpnext/stock/doctype/delivery_note/delivery_note.py b/erpnext/stock/doctype/delivery_note/delivery_note.py
index ea94c7b..30d82ca 100644
--- a/erpnext/stock/doctype/delivery_note/delivery_note.py
+++ b/erpnext/stock/doctype/delivery_note/delivery_note.py
@@ -414,7 +414,6 @@
 	invoiced_qty_map = get_invoiced_qty_map(source_name)
 
 	def set_missing_values(source, target):
-		target.is_pos = 0
 		target.ignore_pricing_rule = 1
 		target.run_method("set_missing_values")
 		target.run_method("set_po_nos")