Change api-ui-source external (e2e_fe)

1. Log in as admin
2. Navigate to advanced settings
3. Change api-ui-source to external
4. Save
5. Refresh page
6. Check page source for dashboard loading location

Expected Results

1. Log in should complete
2. Settings should save
3. dashboard location should be loading from https://releases.rancher.com/harvester-ui/latest
4. (verify it in browser’s developers tools)