Parquet benchmarks fail with multiple threads

Temp file name doesn't have a per-thread (or a random) part, so the benchmarks fail with an "existing file" exception.

**Reporter**: [Gidon Gershinsky](https://issues.apache.org/jira/secure/ViewProfile.jspa?name=gershinsky) / @ggershinsky

_{**Note**: *This issue was originally created as [PARQUET-1483](https://issues.apache.org/jira/browse/PARQUET-1483). Please see the [migration documentation](https://issues.apache.org/jira/browse/PARQUET-2502) for further details.*}

Locate the Parquet benchmark code that creates temporary files and inspect how names are formed when multiple threads run. Run the affected benchmarks with multiple threads; done means concurrent runs no longer fail with an existing-file exception.

Written by the indexing model from the issue text.