Fix broken scripts when TF config comes from envvars

environments/base/inventory/group_vars/all.yml

@@ -26,6 +26,8 @@ terraform_binary_path: "{{ terraform_binary_directory }}/terraform"
 terraform_project_path: "{{ (work_directory, 'terraform') | path_join }}"
 # Get the Terraform backend type from the environment variables
 terraform_backend_type: "{{ lookup('env', 'AZIMUTH_TERRAFORM_BACKEND_TYPE') | default('local', True) }}"
+# By default, assume all Terraform config comes from environment variables
+terraform_backend_config: {}
 
 # Use the configured work directory for prepping manifests
 clusterapi_kustomization_directory: "{{ (work_directory, 'clusterapi') | path_join }}"