Disable Parquet Statistics for signature and hash data

[wilwade]

Problem

Parquet defaults to having statistics for all fields, but it shouldn't have them for hash or signature fields.

Solution

Remove statistics from hash and signature fields

Double Checks:

• [x] Did you update the changelog?
• [x] Any new modules need to be exported?
• [x] Are new methods in the right module?
• [x] Are new methods/modules in core or not (i.e. porcelain or plumbing)?
• [x] Do you have good documentation on exported methods?