The nagflux.log file grows without logrotate and fills the root partition

### Description

As it says in the title, the nagflux.log file (_in /var/log directory_) grows without logrotate and fills the root partition.

The problem is twofold because this file is included in the daily backup which is located in /var/archives and which also fills the root partition.

### Diagnostic

All lines of this log file start with date and **Debug** word like below:
```
[...]
2021-04-08 05:14:50 Debug: 204 No Content
2021-04-08 05:14:50 Debug: 204 No Content
2021-04-08 05:14:55 Debug: Reading Directory: /var/log/nagios/spool/nagfluxperfdata
2021-04-08 05:15:00 Debug: Reading Directory: /var/log/nagios/spool/nagfluxperfdata
2021-04-08 05:15:00 Debug: Reading file: /var/log/nagios/spool/nagfluxperfdata/1617851699.perfdata.host
2021-04-08 05:15:00 Debug: Reading file: /var/log/nagios/spool/nagfluxperfdata/1617851700.perfdata.service
2021-04-08 05:15:05 Debug: Reading Directory: /var/log/nagios/spool/nagfluxperfdata
[...]
```

### Workaround

#### **EDIT:** this logrotate config file doesn't work... ⚠️

~I added the nagflux configuration file (_in /etc/logrotate.d_) with the information below to rotate the log file.~

```
/var/log/nagflux.log {
daily
create 0644 root root
rotate 15
compress
delaycompress
dateext
missingok
notifempty
postrotate
pkill --ns $$ rsyslog -HUP
endscript
}
```