Function apply_oneshot_dbus_override 

pub async fn apply_oneshot_dbus_override(
    connection: &Connection,
    locked_machine_stats: &Arc<RwLock<MachineStats>>,
    config: &UnitsConfig,
)

Apply the oneshot health override to varlink-collected unit stats.

Runs candidate selection under a read lock, resolves service types over D-Bus without holding any lock, then applies the results under a write lock — so D-Bus round trips never block other collectors on the shared MachineStats lock.