fix(stock): remove is_return condition on pos batch qty calculation

(cherry picked from commit 2c19c1fd06)

erpnext/stock/doctype/serial_and_batch_bundle/serial_and_batch_bundle.py

@@ -2609,11 +2609,11 @@ def get_reserved_batches_for_pos(kwargs) -> dict:
 
 		key = (row.batch_no, row.warehouse)
 		if key in pos_batches:
-			pos_batches[key]["qty"] -= row.qty * -1 if row.is_return else row.qty
+			pos_batches[key]["qty"] += row.qty * -1
 		else:
 			pos_batches[key] = frappe._dict(
 				{
-					"qty": (row.qty * -1 if not row.is_return else row.qty),
+					"qty": row.qty * -1,
 					"warehouse": row.warehouse,
 				}
 			)