Close the Flight SQL cursor before the connection

[robinskil]

Problem

Three Flight SQL tests close the connection while a statement stays open. The pinned driver adbc-driver-manager 1.3.0 raises:

RuntimeError: Cannot close AdbcConnection with open AdbcStatement

The assertions pass. Only the teardown step fails.

Failed tests

• test_flight_sql.py::test_flight_select_constant
• test_flight_sql.py::test_flight_query_parquet
• test_flight_sql.py::test_flight_returns_arrow

Task

1. Call cur.close() before conn.close() in each test.
2. Run the file again.

Environment

Branch features/reimplement-atlas. Image beacon-integration:local.