Fix TPCH benchmark setup

[JP-Reddy]

The TPCH benchmark setup (scripts/bench_tpch.sh, scripts/setup_tpch_data.sh, bench_suites/tpch_*) is currently broken and needs to run end-to-end. Once running, 1) we want to confirm the extension inserts CREATE_FILTER/USE_FILTER operators on
every query except the cyclic ones, 2) debug the slow queries, and 3) test at larger scale factors.

Tasks:

• Get the TPCH benchmark setup running end-to-end again (fix setup_tpch_data.sh / bench_tpch.sh).
• Verify the extension inserts CREATE_FILTER/USE_FILTER operators on all queries except the cyclic ones. Use EXPLAIN checks.
• Confirm correctness: every query result with the extension should match baseline.
• Profile and debug the slower queries - identify where the extension hurts or doesn't help.
• Scale-test at sf=1, sf=30, sf=100, and larger; confirm setup, correctness, and operator insertion hold.
• Keep the JFP (join filter pushdown) convention: baseline jfp-on, Robust configs jfp-off.
• Update README.md with the setup + running instructions.