[Security Solution][Detection Engine] fixes empty item_id in exceptio…

…n item update request schema (elastic#194175)

## Summary

- fixes schema for `updateExceptionListItemSchema` , that led to [error
in 8.15](elastic#191315)

8.15 is fixed in elastic#194172, in
separate PR, since 8.16+ error in not reproducible.
But schema still is not correct. So this PR just fixes schema

packages/kbn-securitysolution-io-ts-list-types/src/request/update_exception_list_item_schema/index.ts

@@ -21,6 +21,7 @@ import { description } from '../../common/description';
 import { name } from '../../common/name';
 import { _version } from '../../common/underscore_version';
 import { id } from '../../common/id';
+import { item_id } from '../../common/item_id';
 import { meta } from '../../common/meta';
 import { namespace_type } from '../../common/namespace_type';
 import { ExpireTimeOrUndefined, expireTimeOrUndefined } from '../../common';
@@ -40,7 +41,7 @@ export const updateExceptionListItemSchema = t.intersection([
       comments: DefaultUpdateCommentsArray, // defaults to empty array if not set during decode
       expire_time: expireTimeOrUndefined,
       id, // defaults to undefined if not set during decode
-      item_id: t.union([t.string, t.undefined]),
+      item_id,
       meta, // defaults to undefined if not set during decode
       namespace_type, // defaults to 'single' if not set during decode
       os_types: osTypeArrayOrUndefined, // defaults to empty array if not set during decode