Two windows are opened when using "--startingDirectory" option while no other wt instances are opened

### Windows Terminal version

1.23.10353.0

### Windows build number

10.0.26100.0

### Other Software

cmd
(and any software that can execute "wt -d ..." command)

### Steps to reproduce

1. Have NO Windows Terminal instances opened
2. open cmd
3. type: wt -d "C:\\" or any other location

### Expected Behavior

If no Windows Terminal instances exist Windows Terminal opens a single window with the working directory specified in "-d" option.

### Actual Behavior

If no Windows Terminal instances exist Windows Terminal opens two windows, one is the default working directory (%USERPROFILE% in my case) and one with actual "-d" specified directory.

https://github.com/user-attachments/assets/36bbb8ad-d6ce-4890-a320-f2e6bde73b35

Reproduce the issue from cmd with no Windows Terminal instances running by executing `wt -d "C:\\"`, then trace the startup and window-creation path that handles the `-d` option. Done means the command opens exactly one window using the requested directory rather than also opening the default directory; add or update a regression test if the relevant test location is identified.

Written by the indexing model from the issue text.