Introduce `execution_hint` for Cardinality aggregation (#17312) - backport to 2.x#17419

cwperks merged 3 commits intoopensearch-project:2.xopensearch-project/OpenSearch:2.xfrom

asimmahmood1:backport/backport-17312-to-2.xasimmahmood1/OpenSearch:backport/backport-17312-to-2.xCopy head branch name to clipboard