fix: remove item attribute limit from variant selector (backport #31026) (#31028)

fix: remove item attribute limit from variant selector

(cherry picked from commit 6bd1cb9235)

Co-authored-by: Ankush Menat <me@ankush.dev>

erpnext/stock/doctype/item/item.js

@@ -586,8 +586,7 @@ $.extend(erpnext.item, {
 								["parent","=", d.attribute]
 							],
 							fields: ["attribute_value"],
-							limit_start: 0,
-							limit_page_length: 500,
+							limit_page_length: 0,
 							parent: "Item Attribute",
 							order_by: "idx"
 						}