Influxdb on debian/ubuntu is logging in 3 different files

Continuation of #8319, which was closed but IMHO should not have.

__Steps to reproduce:__
List the minimal actions needed to reproduce the behavior.

1. install influxdb on debian
2. start saving and reading data
3. check the following files:
- /var/log/syslog
- /var/log/user.log
- /var/log/messages

__Expected behavior:__
Influxdb queries should not be present in these files.

__Actual behavior:__
Influxdb queries are logged to these 3 files, quickly filling up the available space on the system.

After disabling query logging in the config file, the logging stops in user.log and messages, but syslog keeps logging.

__Environment info:__

* System info: Run `uname -srm` and copy the output here
`Linux 4.19.0-13-amd64 x86_64`

* InfluxDB version: Run `influxd version` and copy the output here
`InfluxDB v1.8.5 (git: 1.8 3d16c6318cf5)`

* Other relevant environment details: Container runtime, disk info, etc

Debian GNU/Linux 10

__Config:__
Standard config being used.

I disabled HTTP request logging and resarted the service:

```
[http]
# Determines whether HTTP request logging is enabled.
log-enabled = false
```

But queries keep being logged in `journalctl`:

```
journalctl -u influxdb.service -n 10
-- Logs begin at Mon 2021-06-21 18:42:32 CEST, end at Mon 2021-06-21 20:06:10 CEST. --
Jun 21 20:06:10 openwisp-db influxd[22422]: ts=2021-06-21T18:06:10.800680Z lvl=info msg="Executing query" log_id=0UswoFtG000 service=query query="SELECT cpu_usage FROM openwisp2.autogen.cpu WHERE time >= 80m AND
Jun 21 20:06:10 openwisp-db influxd[22422]: ts=2021-06-21T18:06:10.915409Z lvl=info msg="Executing query" log_id=0UswoFtG000 service=query query="SELECT percent_used FROM openwisp2.autogen.memory WHERE time >= 1
```

Start with the standard configuration's [http] log-enabled setting and reproduce the behavior on Debian using the listed log files and `journalctl -u influxdb.service`. Trace why disabling HTTP request logging still emits query entries; done means queries no longer fill `/var/log/syslog`, `/var/log/user.log`, `/var/log/messages`, or the service journal.

Written by the indexing model from the issue text.