Mark shredded_variant cases 41, 131, 132, 138 as INVALID (missing 'value' column) (#117)

These cases omit the required 'value' column from a variant group
(cases 41, 131, 138 at the top level; case 132 in the shredded object
field groups) but were labeled as valid cases. Per the discussion in
apache/parquet-format#591, the spec requires the 'value' field to
always be present, so these files are not spec-compliant.

Relabel them following the existing convention used by cases 43, 84
and 125: '-INVALID' filenames plus a 'notes' entry stating that
implementations can choose to error or read the shredded value. The
expected variant outputs are kept for implementations that choose to
read them.

Fixes #116

Co-authored-by: Claude Fable 5 <noreply@anthropic.com>