Function updater_handle_one_update

async fn updater_handle_one_update(
    statsd: &Client,
    conf: &Conf,
    upwrap: UpWrap,
    service_statuses: &mut HashMap<String, ServiceStatus>,
    chan_outbox_tx: &Sender<QuorumMsg>,
) -> Result<()>

Receives:

• an incoming datapoint from a probe
• a request to generate the dashboard page
• a Change action from the RPC API

Triggers DNS failover / RR change if needed.