Enable Dynamic Values for Elasticsearch Machine Learning Feature (Data Visualizer)

This MR enables helm template directives for node.ml and xpack.ml.enabled values in the elasticsearch.yaml config template and sets their default values to false (as they were before). We are overriding these values in our (JAIC) deployment to true. We need the Data Visualizer functionality (which is enabled as part of the machine learning features of Elasticsearch) in Kibana to be able to easily ingest CSVs through the GUI and these values enable that. The Data Visualizer is part of the free features of Elastic Stack and does not require an enterprise license.

You can read more about this here: https://www.elastic.co/guide/en/kibana/current/xpack-ml.html https://www.elastic.co/blog/importing-csv-and-log-data-into-elasticsearch-with-file-data-visualizer