[BUG] Monitor not showing up when device is up after down state

### Is there an existing issue for this?

- [x] I have searched the existing issues

### Current Behavior

Suppose a device is up (checked manually doing ping) then in hertzbeat it shows as up.
when same device is down (checked manually doing ping) it shows down in hertzbeat UI, but after sometime if device is again "up" then why in hertzbeat UI it still shows as "down", Why its not updating?

### Expected Behavior

Device should update itself as "up" when device comes up after down state abd start collecting metrics.

### Steps To Reproduce

_No response_

### Environment

```markdown
HertzBeat version(s):
```

### Debug logs

_No response_

### Anything else?

_No response_

Start by reproducing the monitor transition from down to up in HertzBeat and trace the monitor status and metric-collection path. There are no files, tests, version details, reproduction steps, or logs in the issue; done means an unreachable device returns to up status and resumes metric collection after it recovers.

Written by the indexing model from the issue text.