[CI] Test Runner: checks if nodes are empty before deleting

Author: picandocodigo

api-spec-testing/test_file.rb

@@ -446,7 +446,7 @@ def wipe_searchable_snapshot_indices(client)
 
         def delete_all_node_shutdown_metadata(client)
           nodes = client.shutdown.get_node
-          return if nodes['_nodes'] && nodes['cluster_name']
+          return if nodes['_nodes'] && nodes['cluster_name'] || nodes&.[]("nodes").empty?
 
           nodes.each do |node|
             client.shutdown.delete_node(node['node_id'])