### Search before asking - [X] I had searched in the [issues](https://github.com/apache/dolphinscheduler/issues?q=is%3Aissue) and found no similar feature requirement. ### Description * Part of #13316  ### Use case * When deployed in K8S, DS worker could scale automatically by the trigger users define. * Give an example of trigger based on the number of task in dispatch & running state. ### Related issues * #13316 * #12436 ### Are you willing to submit a PR? - [X] Yes I am willing to submit a PR! ### Code of Conduct - [X] I agree to follow this project's [Code of Conduct](https://www.apache.org/foundation/policies/conduct)