R1:8bf24f53b334

Destroy surplus columns

Summary:
Ref T1191. This destroys surplus columns:

- Pholio's transaction comments have a `mockID` column, but this is not used. The `imageID` column is used instead.
- Phragment has an unused `description` column.
- Releeph has an unused `summary` column.

Test Plan:
- Grepped for usage of these columns.
- Checked that these exist in production, too.
- Ran upgrades.
- Added Pholio inline comments.
- Saw fewer warnings.

Reviewers: btrahan

Reviewed By: btrahan…