Managed Nodegroups Default

As of eksctl v0.58.0, eksctl creates managed nodegroups by default when a ClusterConfig file isn't specified for eksctl create cluster and eksctl create nodegroup. To create a self-managed nodegroup, pass --managed=false. This may break scripts not using a config file if a feature not supported in managed nodegroups, e.g., Windows nodegroups, is being used. To fix this, pass --managed=false, or specify your nodegroup config in a ClusterConfig file using the nodeGroups field which creates a self-managed nodegroup.