Cannot create a regular user

In the [docker hub page of influxdb](https://hub.docker.com/_/influxdb/) in section **Database Initialization** it is mentioned, that with variables **INFLUXDB_USER** and **INFLUXDB_USER_PASSWORD** I can create a regular user for the specified **INFLUXDB_DB** database. But this does not work.

My `docker-compose.yml` looks like this:
```yaml
version: "3"
services:
influxdb:
container_name: influxdb
restart: unless-stopped
image: influxdb
environment:
- INFLUXDB_DB=testdb
- INFLUXDB_HTTP_AUTH_ENABLED=true
- INFLUXDB_USER=myuser
- INFLUXDB_USER_PASSWORD=mypass
ports:
- "8086:8086"
volumes:
- influx-data:/var/lib/influxdb

volumes:
influx-data:
```
In the log I see, that it does not create the user, but tries to create the database and gets 403, obviously. Eventually, the initialisation fails.

It works fine for the admin user, but I do not want to create a user with full privileges, since I only need to access that particular db.

What am I doing wrong here?

Reproduce the failure with the supplied docker-compose.yml and compare the Docker Hub page’s Database Initialization section with the container logs, focusing on INFLUXDB_USER, INFLUXDB_USER_PASSWORD, and INFLUXDB_DB. Done means the documented configuration either creates the regular user and database successfully or the documentation clearly states the supported behavior and required setup.

Written by the indexing model from the issue text.