TPCH unit tests failure

[vmingchen]

Describe the bug
All unit tests in benchmarks/tpch.rs are failing with errors like this:

Error: External(ArrowError(CsvError("incorrect number of fields for line 1, expected 16 got 17"), None))

To Reproduce
Steps to reproduce the behavior:

cd <BALLISTA_HOME>/benchmarks
./tpch-gen.sh
TPCH_DATA=data cargo test

Expected behavior
All tests should pass with TPCH_DATA=data cargo test

[milenkovicm]

It would be great to fix, issues looks with tbl format, I was adding nullable "dummy" field to each schema to get them converted to parquet