Branding: new loading screens not showing

[kimprice]

Describe the bug I replaced the Arcade icons with Microsoft icons for the loading screens (https://github.com/microsoft/pxt-arcade/pull/5987, https://github.com/microsoft/pxt/pull/9605) but they are not being reflected on beta. The changes are fine when running locally and on upload targets. Will need to do some investigating.

To Reproduce Steps to reproduce the behavior:

1. Go to https://arcade.makecode.com/beta
2. See the initial loading screen shows the old Arcade icon instead of the Microsoft logo
3. Open a project
4. See the loading screen shows the Arcade icon instead of the Microsoft icon

Screenshots Old Arcade icon: