Editor ignores "use native file dialog" setting when run through Steam on Linux

### Tested versions

Reproducible in:
- v4.3.stable.official [77dcf97d8]

### System information

Godot v4.3.stable - Steam Runtime 2 (soldier) 2 - Wayland - Vulkan (Mobile) - dedicated AMD Radeon RX 7600 (RADV NAVI33) - AMD Ryzen 5 7600 6-Core Processor (12 Threads)

### Issue description

When Godot is run through Steam, the editor seems to always use the native file dialogs, even when that option is disabled in the editor settings.

This appears to have started with the most recent Steam client update, which improved Wayland integration (judging by the Steam client now scaling properly).

Note that the same Godot binary run externally from Steam doesn't exhibit this behaviour. So something in the Steam runtime environment appears to be affecting Godot in this way. I tried changing from the Soldier (2) to Scout (1) runtime, but that didn't make a difference.

I also noticed that the native dialog that pops up doesn't seem to be configured correctly, since when *loading* a script file to a Node in the scene tree, the dialog warned me about overwriting the file! :confused:

### Steps to reproduce

1. Be a Linux (+Wayland?) (+KDE?) user;
2. Run Godot editor through Steam;
3. Make sure `Use Native File Dialogs` is disabled in the editor settings;
4. Perform any file access operation, eg. `Scene -> Open Scene`
5. :eyes:

### Minimal reproduction project (MRP)

N/A