R1:42c02557e4e3

Remove all remaining readers and writers for TABLE_COMMIT

Summary: Depends on D20459. Ref T13276. I'll file a followup to actually destroy the table.

Test Plan:
- Grepped for `TABLE_COMMIT`.
- Ran `bin/storage upgrade -f`, got a clean bill of health.

Reviewers: amckinley

Reviewed By: amckinley

Maniphest Tasks: T13276

Differential Revision: https://secure.phabricator.com/D20461