feat: implement database retrieval for builtin provider credentials in ToolManager and update PluginParameterService to use new method

web/app/components/workflow/nodes/_base/components/variable/var-reference-picker.tsx

@@ -328,7 +328,7 @@ const VarReferencePicker: FC<Props> = ({
   const [dynamicOptions, setDynamicOptions] = useState<FormOption[] | null>(null)
   const [isLoading, setIsLoading] = useState(false)
   const { mutateAsync: fetchDynamicOptions } = useFetchDynamicOptions(
-    currentProvider?.plugin_id || '', currentProvider?.name || '', currentTool?.name || '', (schema as CredentialFormSchemaSelect).variable,
+    currentProvider?.plugin_id || '', currentProvider?.name || '', currentTool?.name || '', (schema as CredentialFormSchemaSelect)?.variable || '',
     'tool',
   )
   const handleFetchDynamicOptions = async () => {