[elasticsearch] Add "service.enabled" parameter

[ebuildy]

Describe the feature:

service.yaml should be optional.

Describe a specific use case for the feature:

In case of a pure data nodes Helm release, service is useless (I believe ..).

[jmlrt]

Hi @ebuildy, Elasticsearch chart use 2 different services, the "standard" service which is used for external access and the "headless" service which is mandatory for statefulsets (we had to add one for Logstash charts, see #695 for more details).

While the "headless" need to stay, the "standard" service could be optional, I think we'll need to investigate a bit more to ensure that's OK before creating a PR for that.

[botelastic]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[botelastic]

This issue has been automatically closed because it has not had recent activity since being marked as stale.