Function stale_arecord_label_selector 

pub fn stale_arecord_label_selector(
    current_cluster: &str,
    namespace: &str,
    ingress_name: &str,
) -> String

Builds a label selector string matching ARecords for the given Ingress that belong to any cluster other than current_cluster.

Used to detect and clean up stale ARecords left behind when the scout is restarted with a different --cluster-name. The != operator is supported by the Kubernetes label selector language for equality-based requirements.