Why was "--sandbox-image" removed?

[oliverfleetwood]

The flag --sandbox-image has been removed from Gemini CLI. Why? This was a very useful way to share functionality between projects and users. The file sandbox.Dockerfile in your project's .gemini is not as useful since we need one file per project + it is much more work to build it. It would be much simpler if you can share your image between projects and/or download your image from an in-house repository.
This PR removed the flag, but I can't find any documentation on corresponding support in settings.json.

[oliverfleetwood]

Got this to work using the env param GEMINI_SANDBOX_IMAGE. Still can't find the name of the property in settings.json though