Set compatibility mode to use beats

Summary:
Reference:
https://opensearch.org/docs/latest/clients/agents-and-ingestion-tools/index/

Ref T1624

Test Plan: Define setting through _cluster/settings REST API on CloudHugger

Reviewers: dereckson

Reviewed By: dereckson

Maniphest Tasks: T1624

Differential Revision: https://devcentral.nasqueron.org/D2452