R1:060f96079def

Fix Diffusion blame columns when disabling blame

Summary:
Fixes T10385. Two issues:

- `$show_blame` and `$show_color` were improperly swapped.
- Code to hide these columns got dropped somewhere, probably in my recent-ish rewrite.

Test Plan:
- Showed/hid blame.
- Showed/hid colors.

Reviewers: chad

Reviewed By: chad

Maniphest Tasks: T10385

Differential Revision: https://secure.phabricator.com/D15528