Codespaces: Debugging is broken

Steps to repro:

- Create a new Codespace **in Web** using a repo with launch.json. Eg: https://github.com/microsoft/vscode-remote-try-node
- Start debugging (Press `F5`)

🐛 Prompts to select the debugger type

![image](https://user-images.githubusercontent.com/10746682/133475379-48696ff6-3cc3-4b66-b4c0-2a78eaaf1cd5.png)

Expected: Starts debugging without any prompts
