ingest_unmanaged_parquet litters /tmp with .parquet files

[MichaelTiemannOSC]

For debugging purposes, I can see why one might want to have a parquet file in /tmp to examine, but none of the utils files clean up WORKDIR after operation, leading to lots of litter collecting in /tmp. I think we need a better garbage collector than "just go into the shell and remove all the dead .parquet files in /tmp".

[erikerlandson]

closing this - see #14