refactor: move RFQ supplier disabled filter to link_filters

Static filters with no doc-dependent values belong on the field
definition, not in JS. Matches the existing pattern used for
Warehouse/Item link_filters elsewhere (e.g. job_card_item.json,
product_bundle_item.json).

erpnext/buying/doctype/request_for_quotation/request_for_quotation.js

@@ -22,10 +22,6 @@ frappe.ui.form.on("Request for Quotation", {
 			};
 		};
 
-		frm.set_query("supplier", "suppliers", function () {
-			return { filters: { disabled: 0 } };
-		});
-
 		frm.set_query("warehouse", "items", () => ({
 			filters: {
 				company: frm.doc.company,

erpnext/buying/doctype/request_for_quotation_supplier/request_for_quotation_supplier.json

@@ -40,6 +40,7 @@
    "fieldtype": "Link",
    "in_list_view": 1,
    "label": "Supplier",
+   "link_filters": "[[\"Supplier\",\"disabled\",\"=\",0]]",
    "options": "Supplier",
    "reqd": 1
   },