[ui/utils/query_string]: Remove unused methods & migrate apps to quer…

…ystring lib (elastic#56957)

This was already backported, but changes to endpoint app could not be
backported, since endpoint app itself hadn't been backported. Now that
the endpoint app is backported, reapply the endpoint specific changes
from the original commit.

x-pack/plugins/endpoint/public/applications/endpoint/store/alerts/middleware.ts

@@ -4,13 +4,13 @@
  * you may not use this file except in compliance with the Elastic License.
  */
 
-import qs from 'querystring';
+import { parse } from 'query-string';
 import { HttpFetchQuery } from 'src/core/public';
 import { AppAction } from '../action';
 import { MiddlewareFactory, AlertListData } from '../../types';
 
 export const alertMiddlewareFactory: MiddlewareFactory = coreStart => {
-  const qp = qs.parse(window.location.search.slice(1));
+  const qp = parse(window.location.search.slice(1), { sort: false });
 
   return api => next => async (action: AppAction) => {
     next(action);