fix(ops): use --format pretty for docker config inspect in rabbitmq.sh

Replace base64 decoding approach with --format pretty to match deploy.sh
and fix 'base64: invalid input' error in GitHub Actions.

Author: elimelt

s/ops/rabbitmq.sh

@@ -45,7 +45,7 @@ create_user() {
   container_id=$(get_rabbitmq_container)
 
   log INFO "Loading credentials from Docker config: $config_name"
-  docker config inspect "$config_name" --format '{{.Spec.Data}}' | base64 -d > /tmp/${svc}_env.tmp
+  docker config inspect "$config_name" --format pretty | grep '=' > /tmp/${svc}_env.tmp || true
 
   local rabbit_user rabbit_pass rabbit_vhost