Terminal Logger is enabled in GitHub Copilot workstreams

[rainersigwald]

In https://github.com/dotnet/msbuild/pull/12014/agent-sessions/97b76408-c604-49f6-8767-39bbe64805a8, scroll down to Let me try to build the Framework project to ensure my documentation changes don't break. The console output below that is clearly from our terminal logger:

But in this context, we would ideally auto-detect that the output isn't "a terminal emulator in front of a human" and fall back to classic logging.