Function extract_auto_scaling_strategy 

pub(crate) fn extract_auto_scaling_strategy(
    create_stmt: &CreateClusterStatement<Raw>,
) -> Result<Option<AutoScalingStrategy>, String>

Extract the desired autoscaling policy from a CreateClusterStatement’s options. An absent option and an empty AUTO SCALING STRATEGY = () block both map to None (no policy), matching the server planner’s normalization.