Run container as non root (2)

[BobyMCbobs]

Goal

This PR removes extra dependencies in the container image to run as a non-root user, instead defaulting all processes to run as root from the entrypoint.
This is important, as an exec's into the container image will not run as root, unlike currently.

Changes

Please describe the changes made in the pull request here.

Below you'll find a checklist. For each item on the list, check one option and delete the other.

Tests

• Automated tests have been added
• This PR does not require tests

Changelog

• Entry has been added to changelog
• This PR does not make a user-facing change

Documentation

• Docs have been updated
• This change does not need a documentation update

---

Notes

The changes of the previous PR were regressed due to #360.

Initialising succeeds from the following commands:

        command:
        - /bin/sh
        - -c
        - /entrypoint.sh db createdb && /entrypoint.sh db migrate && /entrypoint.sh db init-admin

and shows the logs

# kubectl -n plausible logs plausible-5689584dd5-pt5zs -c plausible-init
Loading plausible..
Starting dependencies..
Starting repos..
create Plausible.Repo database if it doesn't exist
create Plausible.ClickhouseRepo database if it doesn't exist
Creation of Db successful!
Loading plausible..
Starting dependencies..
Starting repos..
Running migrations for Elixir.Plausible.Repo
Running migrations for Elixir.Plausible.ClickhouseRepo
Migrations successful!
Loading plausible..
Starting dependencies..
Starting repos..
Admin user already exists. I won't override, bailing

[ukutaht]

Looks good to me

[BobyMCbobs]

Looks good to me

Thank you, @ukutaht!