Function stale_httproute_arecord_label_selector 

pub fn stale_httproute_arecord_label_selector(
    current_cluster: &str,
    namespace: &str,
    route_name: &str,
) -> String

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

Used to detect and clean up stale ARecords left behind when scout is restarted with a different --cluster-name.