Support more elasticsearch versions

What does this MR do?

Makes Elasticsearch v5.2.x and v5.3.x officially supported

Are there points in the code the reviewer needs to double check?

Why was this MR needed?

Customers are asking for us to support later versions.

Screenshots (if relevant)

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated
• Tests
  • All builds are passing
• Conform by the merge request performance guides
• Conform by the style guides
• Branch has no merge conflicts with master (if it does - rebase it please)
• Squashed related commits together

What are the relevant issue numbers?

Closes #2253 (closed)