Update the feature stage to our definition

[scheeles]

In some cases we still us Experimental
https://docs.kubermatic.com/kubermatic/v2.27/architecture/supported-providers/baremetal/

Let's align them to the definition
https://docs.kubermatic.com/kubermatic/v2.27/architecture/feature-stages/