[Proposal] Provide a lite version of SDK for CI/CD

### Use case

I'm a DevOps-Engineer and use the Flutter SDK inside of Docker images used in CI/CD pipelines.

The normal installation process involves downloading and unzipping https://storage.googleapis.com/flutter_infra_release/releases/stable/linux/flutter_linux_3.27.1-stable.tar.xz, which includes a 130 MB .git directory, examples, documentation, tests and a few other things.

The directories are probably there so you can update to the latest SDK version by running `flutter channel stable`, which just pulls the latest commits from the `stable` git branch but in my case, I don't need the update functionality.

To reduce my build image size, I currently clone a specific version tag and then remove files manually.

### Proposal

Offer an additional lightweight SDK zip for CI environments and either:

- Publish it alongside the current SDK zip
- Replace the current SDK zip with the lightweight one and add instructions on how to enable the update functionality
- Replace the current SDK zip with the lightweight one and change the update functionality so it doesn't rely on git