[Transform] add actual timeout in message (#50140)

add the timeout to the message if stopping a transform times out

Author: Hendrik Muhs

x-pack/plugin/transform/src/main/java/org/elasticsearch/xpack/transform/action/TransportStopTransformAction.java

@@ -398,7 +398,9 @@ private void waitForTransformStopped(
                     if (stillRunningTasks.size() > 0) {
                         message.append("Could not stop the transforms ");
                         message.append(stillRunningTasks);
-                        message.append(" as they timed out.");
+                        message.append(" as they timed out [");
+                        message.append(timeout.toString());
+                        message.append("].");
                     }
 
                     listener.onFailure(new ElasticsearchStatusException(message.toString(), RestStatus.REQUEST_TIMEOUT));