OOBE: Default settings not applied

### Bug description

It doesn't seem possible to create a default configuration to disable the popups shown at first launch.

It seems that this used to work, but now it doesn't https://forum.audacityteam.org/t/remove-welcome-to-audacity-nag-screen/28822/8

### Steps to reproduce

1. Install audacity
Download audacity 3.7.7 and run `audacity-installer.exe /VERYSILENT /NORESTART`
3. Place audacity.cfg into config dir:
```
SendAnonymousUsageInfo=0

[Version]
Major=3
Minor=7
Micro=7

[GUI]
ShowWelcome=0
ShowSplashScreen=0
[Update]
DefaultUpdatesChecking=0
UpdateNoticeShown=1
```
3. Launch audacity
4. Popup about updates and UUIDs is shown
5. Welcome screen is shown
6. Close audacity
7. Replace the content in the config file with the config above again
8. Launch audacity
9. Settings are applied

You can repeat this by running `audacity-installer.exe /VERYSILENT /NORESTART` again and placing the config in the directory.
### Expected behavior

The settings should apply on first launch

### Actual behavior

The settings are ignored on first launch after install or update. If you replace the config file after first launch, the are applied correctly.

### Audacity Version

Audacity 3.7.7

### Operating system

Windows

### Additional context

_No response_

### Possibly related issues
https://github.com/audacity/audacity/issues/10472 https://github.com/audacity/audacity/issues/10601

Reproduce the issue with audacity-installer.exe /VERYSILENT /NORESTART, audacity.cfg, and the listed Audacity 3.7.7 settings on Windows. Trace the first-launch configuration path and compare it with the second launch after replacing audacity.cfg; done means the settings apply before the update, UUID, and welcome popups appear.

Written by the indexing model from the issue text.