When creating a fresh EC2 Autoscaling group, it turned out that "instance profile" isn't the same as "instance role". On Prod we created it using AWS Console, which automatically created the instance profile.
When creating it using terraform (AWS API in general), we need to create the instance profile separately and attach the role to it.
AWS Docs: https://docs.aws.amazon.com/IAM/latest/UserGuide/id_roles_use_switch-role-ec2_instance-profiles.html
For production, imported the existing instance profile resource using `terraform import`.
Depends on D8715.