Fix Databricks empty SELECT response type

[ianu82]

Summary

• update Databricks native_query to return RESPONSE_TYPE.TABLE whenever result-set metadata (cursor.description) exists, even when the rowset is empty
• keep RESPONSE_TYPE.OK for statements that do not return a result set
• add a regression test for empty SELECT behavior

Why

Empty SELECT queries were incorrectly classified as OK, which hides schema information and causes downstream metadata/table handling inconsistencies.

Validation

• python3 -m py_compile mindsdb/integrations/handlers/databricks_handler/databricks_handler.py tests/unit/handlers/test_databricks.py
• pytest -q tests/unit/handlers/test_databricks.py -k empty_select_returns_table (fails in this environment due to missing optional dependency appdirs)

[github-actions]

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[ianu82]

recheck