Imported WSL instance not discovered until Terminal is restarted

### Windows Terminal version

Windows Terminal Preview Version: 1.21.1272.0

### Windows build number

10.0.22631.0

### Other Software

```
PS C:\Users\timbl> wsl.exe --version
WSL version: 2.1.5.0
Kernel version: 5.15.146.1-2
WSLg version: 1.0.60
MSRDC version: 1.2.5105
Direct3D version: 1.611.1-81528511
DXCore version: 10.0.25131.1002-220531-1700.rs-onecore-base2-hyp
Windows version: 10.0.22631.3593
```

### Steps to reproduce

1. Export a WSL2 machine as a .tar.gz. As in #17262, I'm doing this with nixos-wsl's tarball builder.
2. Import it: `wsl.exe --import %USERPROFILE%\nixos-wsl-tarballs\ `
3. In Terminal, click _v_ and see it is not possible to open the new wsl machine's profile.
4. Restart Terminal, and see that the new wsl machine's profile is available and functional.

### Expected Behavior

Step 4. above should not be required. In 3, after importing the wsl machine, it should be possible to open it without restarting Terminal.

I would understand if this behavior is "as-designed" and therefore this converted to a feature request.

### Actual Behavior

See #Steps To Reproduce.

Start by reproducing the issue with the listed WSL import command and compare profile availability before and after restarting Terminal. Trace the Terminal path that discovers or refreshes WSL instances; done means an imported instance appears and opens immediately without a restart.

Written by the indexing model from the issue text.