Merge branch 'remove-opentofu-support' into 'master'

feat: remove OpenTofu support

See merge request https://gitlab.com/gitlab-org/terraform-images/-/merge_requests/257



Merged-by: João Alexandre Cunha <j.a.cunha@gmail.com>
Approved-by: João Alexandre Cunha <j.a.cunha@gmail.com>
Co-authored-by: Timo Furrer <tfurrer@gitlab.com>