Switching MESA_D3D12_DEFAULT_ADAPTER_NAME to NVIDIA defaults to llvmpipe rendering

### Windows Version

Microsoft Windows [Version 10.0.26100.2605]

### WSL Version

2.3.26.0

### Are you using WSL 1 or WSL 2?

- [x] WSL 2
- [ ] WSL 1

### Kernel Version

5.15.167.4-1

### Distro Version

Ubuntu 24.04

### Other Software

_No response_

### Repro Steps

Steps were followed from [here](https://github.com/microsoft/wslg/wiki/GPU-selection-in-WSLg)
`sudo apt install mesa-utils`
`nvidia-smi`
`MESA_D3D12_DEFAULT_ADAPTER_NAME=NVIDIA glxinfo | grep "OpenGL renderer"`

### Expected Behavior

The following output should be present:
```bash
MESA: error: ZINK: failed to choose pdev
glx: failed to create drisw screen
OpenGL renderer string: D3D12 (NVIDIA GeForce RTX 4060 Laptop GPU)
```

### Actual Behavior

The following output is given by running the `glxinfo` command as outlined in "Repro Steps":
```bash
MESA: error: ZINK: failed to choose pdev
glx: failed to create drisw screen
OpenGL renderer string: llvmpipe (LLVM 17.0.6, 256 bits)
```
Running the same command without the env variable gives the following:
```bash
MESA: error: ZINK: failed to choose pdev
glx: failed to create drisw screen
OpenGL renderer string: D3D12 (Intel(R) Arc(TM) Graphics)
```
It uses the integrated graphics card but refuses to use the Nvidia Graphics card despite `nvidia-smi` detecting it.
How can I get it to use the Nvidia Graphics card?

### Diagnostic Logs

[WslLogs-2024-12-26_17-48-04.zip](https://github.com/user-attachments/files/18250383/WslLogs-2024-12-26_17-48-04.zip)

Start by reproducing the issue with the documented WSLg GPU-selection steps, especially nvidia-smi and the MESA_D3D12_DEFAULT_ADAPTER_NAME=NVIDIA glxinfo command. Inspect the attached WslLogs-2024-12-26_17-48-04.zip and compare the NVIDIA-selected and default renderer paths; done means the command reports the NVIDIA D3D12 renderer rather than llvmpipe.

Written by the indexing model from the issue text.