refactor(states): Replace jQuery with dom utils in states (@thanoskn) (#7314)

### Description

Replaced jQuery with dom utils

### Checks

- [x] Adding/modifying Typescript code?
  - [x] I have used `qs`, `qsa` or `qsr` instead of JQuery selectors.
- [x] Check if any open issues are related to this PR; if so, be sure to
tag them below.
- [x] Make sure the PR title follows the Conventional Commits standard.
(https://www.conventionalcommits.org for more info)
- [x] Make sure to include your GitHub username prefixed with @ inside
parentheses at the end of the PR title.

### Related issue #7186 , #7319

Author: thanoskn

frontend/src/ts/states/connection.ts

@@ -2,6 +2,7 @@ import { debounce } from "throttle-debounce";
 import * as Notifications from "../elements/notifications";
 import * as ConnectionEvent from "../observables/connection-event";
 import * as TestState from "../test/test-state";
+import { qs, onWindowLoad } from "../utils/dom";
 
 let state = navigator.onLine;
 
@@ -33,9 +34,9 @@ const throttledHandleState = debounce(5000, () => {
       Notifications.add("You're back online", 1, {
         customTitle: "Connection",
       });
-      $(
+      qs(
         `#bannerCenter .psa.notice[id="${noInternetBannerId}"] .closeButton`,
-      ).trigger("click");
+      )?.dispatch("click");
     }
     bannerAlreadyClosed = false;
   } else if (!TestState.isActive) {
@@ -48,7 +49,7 @@ ConnectionEvent.subscribe((newState) => {
   throttledHandleState();
 });
 
-window.addEventListener("load", () => {
+onWindowLoad(() => {
   state = navigator.onLine;
   if (!state) {
     showOfflineBanner();