ElasticSearchGraphService should work with no relationship types

[EnricoMi]

The GraphService API provides two methods findRelatedEntities and removeEdgesFromNode that allow to provide a list of relationship types. When that list is empty, the methods should no-op and return immediately.

The current ElasticSearch implementation does not show this behaviour.

There are tests in #3011 that test this behaviour.

[maggiehays]

Hi @EnricoMi!

We are now managing feature requests through our new portal to improve visibility & prioritize work into our public roadmap. If this request is still relevant, please create a new issue so we can gauge current interest from the Community & prioritize work accordingly.

We'll close out this issue in the meantime. Feel free to reach out to me on DataHub Slack with any questions!