Add more services to exclusion list

- Add docker-prune (cleanup services don't need monitoring)
- Add sshd-unix-local@ and sshd@ (SSH instance services)
- Add docker-registry-gar (Google Artifact Registry services)
- Keep main sshd service monitored while excluding per-connection instances

agent/src/collectors/systemd.rs

@@ -149,6 +149,10 @@ impl SystemdCollector {
             "mosquitto-backup",
             "nginx-config-reload",
             "sshd-keygen",
+            "sshd-unix-local@",
+            "sshd@",
+            "docker-prune",
+            "docker-registry-gar",
         ];
 
         // Define patterns for services we want to monitor (from legacy)