cli: remove registry_auth for Docker Terraform module

[Nirusu]

Proposed change(s)

• Remove registry_auth for Docker Terraform provider

This seems to be a leftover from back when the repoistory and images were private, but causes Mini Constellation to fail when no config.json for Docker exists under the defined path ~/docker/config.json.

Related issue

Trying to run MiniConstellation on a relatively fresh Docker installation where this config file does not exist, you will get this error:

./constellation-linux-amd64 mini up
A config file already exists in the current workspace.
Do you want to overwrite it? [y/n]: y
Creating cluster in QEMU   
An error occurred: exit status 1

Error: Error loading registry auth config: could not open config file from filePath: /home/ubuntu/.docker/config.json. Error: open /home/ubuntu/.docker/config.json: no such file or directory

  with provider["registry.terraform.io/kreuzwerker/docker"],
  on main.tf line 18, in provider "docker":
  18: provider "docker" {

Checklist

• Backport the changes to release/v2.4 (in backport: changes for v2.4.1 #956)

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[malt3]

Nice catch! I added a checklist item to backport this to v2.4.1 (@3u13r)