fix: Fix storybook (no-changelog) (#4624)

since we migrated to vite, storybook/webpack aren't doing all the babel transforms. that's we we need to revert all optional-chaining and nullish-coalescing in design-system.

Hopefully this will be remedied after we move to vite for storybook.

packages/design-system/src/components/N8nFormInput/FormInput.vue

@@ -128,10 +128,10 @@ const slots = useSlots();
 const inputRef = ref<HTMLTextAreaElement | null>(null);
 
 function getInputValidationError(): ReturnType<IValidator['validate']> {
-	const rules = props.validationRules ?? [];
+	const rules = props.validationRules || [];
 	const validators = {
 		...VALIDATORS,
-		...(props.validators ?? {}),
+		...(props.validators || {}),
 	} as { [key: string]: IValidator | RuleGroup };
 
 	if (props.required) {