Migrate terraform-module to use standard autodevops stages

Follow-up from uis/devops/infra/terraform/gcp-secret-manager!11 (comment 565461)

The current terraform-module.yml include-s GitLab's Terraform-Module template. This template defines a load of CI stages and wraps GitLab's Terraform/Module-Base template.

CI stages cannot currently be extended and so terraform-module.yml, in effect, defines its own stages and thereby breaks composability with other CI templates such as /autodevops/release-it.yml.

Move terraform-module.yml over to using Terraform/Module-Base directly and include the /autodevops-stages.yml template so that we retain composability.