fluentd_output_status_num_errors sould be counter

### Describe the bug

prometheus metric fluentd_output_status_num_errors is exposed as gauge
but its behavior is more like a counter.

### To Reproduce

enable prometheus metric in fluentd and read /metrics for
`fluentd_output_status_num_errors`

### Expected behavior

to have this metrics exported as a counter with a proper counter name,

### Your Environment

```markdown
- Fluentd version: v1.18
- Package version: v1.18
- Operating system: debian
- Kernel version: ?
```

### Your Configuration

```apache
config:
- source:
$type: prometheus
bind: 0.0.0.0
port: 24231
metrics_path: /metrics
- source:
$type: prometheus_output_monitor
interval: 10
labels:
hostname: ${hostname}
- source:
```

### Your Error Log

```shell
no error
```

### Additional context

_No response_