FR: k8s refresh hostname from annotation

### What are you trying to do?

It's possible to set the hostname of a loadbalancer using

```cue
metadata: annotations: "tailscale.com/hostname": "some-name"
```

The hostname does not update if the annotation is changed however. The only way to force a refresh is to delete the secret and statefulset associated with the lb.

### How should we solve this?

It may be possible to watch for changes to the resource - at a minimum, it should check the hostname when the pod for the statefulset or operator is restarted.

### What is the impact of not solving this?

It will be tedious to change the hostname of an lb service.

### Anything else?

_No response_