Migration dialog can once again be accessed when an account is not ready for migration

The bug

Between 2.2.116x and 2.2.14xx, the migration dialog could not be accessed in the Launcher at all. However, in 2.2.176x, the dialog can be accessed once again, even if your account is not ready to be migrated.

How to reproduce

I will keep the reproduction steps in a private ticket for now. Please see MCL-16237 or MCL-16242 (private) if you'd like to test this issue. Note that you may need to save and reopen the launcher an extra time to reproduce now.

If you're a mod/Mojang and you'd like reproduction steps provided here, please set this ticket to private, and then I'll add them