reduce noisy logs.

Reduce noisy logs.

Is this log even necessary:
```
2025-11-01 02:22:54.947Z INFO propolis-server/8267 (vm_state_driver) on oxz_propolis-server_48d5fe36-ee05-4afc-bcca-b1adba223de7:  8903938 final dependency list [[]]
     = downstairs
    client = 1
    session_id = 9d2c04f7-b032-4ca8-af79-193172dd24fe
```

If it's empty, we could just skip printing it.