fix: OpenSearch-3.x SQL stopped supporting DSL-format SQL JSON

[davidsbatista]

Related Issues

• fixes #2857

Proposed Changes:

• The new OpenSearch changed since 3.x onwards.
• SQL responses are still JSON, but no longer the legacy DSL-shaped JSON (i.e.: with hits, _shards, aggregations) returned via format=json in 2.x.
• Updated the OpenSearch SQL integration tests to use a docker with OpenSearch 3.5.
• Updated tests to validate the tabular SQL JSON format (schema, datarows, size, status, optional cursor).

How did you test it?

• updated all the SQL-related tests (both sync and async) to assert for a different output, still JSON, just no longer in a DSL-shaped format

Notes for the reviewer

• Our OpenSearchDocumentStore will still work with OpenSearch 2.x, the only change was in the sql_query method where the params = {"format": "json"} was removed.
• Both run() and run_async() from the OpenSearchSQLRetriever just return the result from the SQL call, so there's no breaking changes introduced

Checklist

• I have read the contributors guidelines and the code of conduct
• I have updated the related issue with new insights and changes
• I added unit tests and updated the docstrings
• I've used one of the conventional commit types for my PR title: fix:, feat:, build:, chore:, ci:, docs:, style:, refactor:, perf:, test:.

[anakin87]

👍