Allow custom docker and runner sections in AWS

As implemented for GCP add custom controls to the docker and runner sections of the config.toml: https://gitlab.com/gitlab-org/ci-cd/runner-tools/grit/-/blob/f3b71e6336e6c204cc9c082fde231dc696806ed5/modules/google/runner/prod/variables.tf#L138-143 for AWS runners.

This would also remove the privileged flag.