Unblocking [RUST-INT][TPCH]: Add a call to .combine_chunks() when creating a Table from arrow

[jaychia]

• When we create Tables from PyArrow tables, we can only handle one batch at the moment
• This causes some issues when running our TPC-H unit tests, ostensibly because the parquet files define multiple Parquet row groups
• This PR adds a temporary fix to unblock running our new Rust code on TPC-H by calling to .combine_chunks() before creating the table so that we only have one batch