fix(UX): Optimize rate updation of changing price list

(cherry picked from commit 6087d5a6038d6e636ce1ba006ebd59e820b3cd8e)
diff --git a/erpnext/stock/get_item_details.py b/erpnext/stock/get_item_details.py
index 9889a22..06f8fa7 100644
--- a/erpnext/stock/get_item_details.py
+++ b/erpnext/stock/get_item_details.py
@@ -1097,7 +1097,7 @@
 		}
 
 def apply_price_list_on_item(args):
-	item_doc = frappe.get_doc("Item", args.item_code)
+	item_doc = frappe.db.get_value("Item", args.item_code, ['name', 'variant_of'], as_dict=1)
 	item_details = get_price_list_rate(args, item_doc)
 
 	item_details.update(get_pricing_rule_for_item(args, item_details.price_list_rate))