Use influxdb-management for managing InfluxDB

What does this MR do?

This updates the InfluxDB documentation so it suggests using https://gitlab.com/gitlab-org/influxdb-management instead of requiring users to manually copy-paste queries into an InfluxDB shell.

Are there points in the code the reviewer needs to double check?

Mostly spelling and if the writing style makes sense.

Why was this MR needed?

The same list of queries was duplicated in multiple places and it was hard to manually keep this up to date.

Does this MR meet the acceptance criteria?

• CHANGELOG entry added Not really tied into a version
• Documentation created/updated
• Conform by the style guides
• Branch has no merge conflicts with master (if you do - rebase it please)
• Squashed related commits together