Remove spurious AppSubUrl in serviceworker request. (#16047)

There is another spurious AppSubUrl placement in the serviceworker registration.
This PR removes it.

Signed-off-by: Andrew Thornton <art27@cantab.net>

web_src/js/features/serviceworker.js

@@ -1,6 +1,6 @@
 import {joinPaths} from '../utils.js';
 
-const {UseServiceWorker, AppSubUrl, AssetUrlPrefix, AppVer} = window.config;
+const {UseServiceWorker, AssetUrlPrefix, AppVer} = window.config;
 const cachePrefix = 'static-cache-v'; // actual version is set in the service worker script
 const workerAssetPath = joinPaths(AssetUrlPrefix, 'serviceworker.js');
 
@@ -41,10 +41,9 @@ export default async function initServiceWorker() {
     // unregister all service workers where scriptURL does not match the current one
     await unregisterOtherWorkers();
     try {
-      // normally we'd serve the service worker as a static asset from AssetUrlPrefix but
-      // the spec strictly requires it to be same-origin so it has to be AppSubUrl to work
+      // the spec strictly requires it to be same-origin so the AssetUrlPrefix should contain AppSubUrl
       await checkCacheValidity();
-      await navigator.serviceWorker.register(joinPaths(AppSubUrl, workerAssetPath));
+      await navigator.serviceWorker.register(workerAssetPath);
     } catch (err) {
       console.error(err);
       await invalidateCache();