### Describe Your Changes
It is better to show only unhealthy targets instead of all of them when
`show_only_unhealthy` filter is enabled.
Related issue:
https://github.com/VictoriaMetrics/VictoriaMetrics/issues/3536
### Checklist
The following checks are **mandatory**:
- [x] My change adheres [VictoriaMetrics contributing
guidelines](https://docs.victoriametrics.com/contributing/).
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Co-authored-by: Roman Khavronenko <roman@victoriametrics.com>