Add option to disable automatic template/ILM policy creation for data streams

[Lukas-Ldc]

Is your feature request related to a problem? Please describe.

When using data streams with fluent-plugin-elasticsearch, templates and ILM policies are automatically created. This causes several issues:

1. Manual cleanup required: We need to clean up the automatically created templates and policies in Elasticsearch.

2. Indexing conflicts: The auto-generated templates sometimes conflict with existing templates, causing multiple sources to match the same template. Also, when I forget to clean up and create my own template, it conflicts with the auto-generated one, blocking indexing.

Describe the solution you'd like

Could you please add a configuration parameter to skip automatic template and ILM policy creation for data streams.

Example:

<match **>
  @type elasticsearch_data_stream
  data_stream_name my-stream
  
  template_auto_create false
  ilm_policy_auto_create false
</match>