[Glitch] Change how CDN_HOST is passed down to make assets build reproducible

Port 4c45b43cb8 to glitch-soc

Signed-off-by: Thibaut Girka <thib@sitedethib.com>

app/javascript/core/admin.js

@@ -1,6 +1,6 @@
 //  This file will be loaded on admin pages, regardless of theme.
 
-import './public-path';
+import 'packs/public-path';
 import { delegate } from '@rails/ujs';
 import ready from '../mastodon/ready';