Confirmation

• I confirm that I am a maintainer and so can use this template. If I am not, I understand this issue will be closed and I will be asked to use a different template.

Issue body

The MagenticOne team uses local code execution by default.

DockerCodeExecution should be default and we should stop users from trying to run it if they don't have docker installed.

https://github.com/microsoft/autogen/blob/main/python/packages/autogen-ext/src/autogen_ext/teams/magentic_one.py