Remove worker-loader (#23548)

[`worker-loader`](https://github.com/webpack-contrib/worker-loader) is
deprecated since webpack 5 which can load workers without it now, so
remove it. I think it was already dysfunctional because the regex does
not match our current worker scripts:

```
web_src/js/features/eventsource.sharedworker.js
web_src/js/features/serviceworker.js
web_src/js/serviceworker.js
```

I did confirm that eventsource worker still loads via simple
`console.log` inside the script.

Co-authored-by: delvh <leon@kske.dev>

package.json

@@ -47,7 +47,6 @@
     "webpack-cli": "5.0.1",
     "workbox-routing": "6.5.4",
     "workbox-strategies": "6.5.4",
-    "worker-loader": "3.0.8",
     "wrap-ansi": "8.1.0"
   },
   "devDependencies": {