Cleanup `awaiting_status` in case we don't have remaining subscriptions

We always replaced it with `remaining`, but when populating `awaiting_status` upon sync we only go by the keys, so we actually fill in the script status again.
We should remove the complete entry if we want to make sure that we don't want to process it anymore.

Note: Kept seeing monitoring logs for things that were already past Finality (...) so we looked into this.

daemon/src/monitor.rs

@@ -383,7 +383,11 @@ where
 
                     tracing::trace!("{} subscriptions reached their monitoring target, {} remaining for this script", reached_monitoring_target.len(), remaining.len());
 
-                    occupied.insert(remaining);
+                    if remaining.is_empty() {
+                        occupied.remove();
+                    } else {
+                        occupied.insert(remaining);
+                    }
 
                     for (target_status, event) in reached_monitoring_target {
                         tracing::info!(%txid, target = %target_status, current = %status, "Bitcoin transaction reached monitoring target");
@@ -722,6 +726,37 @@ mod tests {
         assert!(!recorder.events.contains(&refund_finality));
     }
 
+    #[tokio::test]
+    async fn stop_monitoring_after_target_reached() {
+        let _guard = tracing_subscriber::fmt()
+            .with_env_filter("trace")
+            .with_test_writer()
+            .set_default();
+
+        let (recorder_address, mut recorder_context) =
+            xtra::Context::<MessageRecordingActor>::new(None);
+        let mut recorder = MessageRecordingActor::default();
+
+        let cet_finality = Event::CetFinality(OrderId::default());
+
+        let mut monitor = Actor::for_test(
+            recorder_address,
+            [(
+                (txid1(), script1()),
+                vec![(ScriptStatus::finality(), cet_finality.clone())],
+            )],
+        );
+        monitor.client.include_tx(txid1(), 5);
+
+        recorder_context
+            .handle_while(&mut recorder, monitor.sync())
+            .await
+            .unwrap();
+
+        assert!(recorder.events.contains(&cet_finality));
+        assert!(monitor.awaiting_status.is_empty());
+    }
+
     impl<A> Actor<A, stub::Client>
     where
         A: xtra::Actor + xtra::Handler<Event>,