packer: make subscribing optional

We don't want to subscribe Fedora.

Signed-off-by: Ondřej Budai <ondrej@budai.cz>

templates/packer/ansible/roles/common/files/worker-initialization-scripts/subscription_manager.sh

@@ -4,6 +4,11 @@ source /tmp/cloud_init_vars
 
 echo "Subscribing instance to RHN."
 
+if [[ -z "$SUBSCRIPTION_MANAGER_COMMAND_ARN" ]]; then
+  echo "SUBSCRIPTION_MANAGER_COMMAND_ARN not defined, skipping."
+  exit 0
+fi
+
 # Register the instance with RHN.
 # TODO: don't store the command in a secret, only the key/org-id
 /usr/local/bin/aws secretsmanager get-secret-value \