Remove `@group` annotations

Summary: I'm pretty sure that `@group` annotations are useless now... see D9855.

Test Plan: Eye-ball it.

Reviewers: epriestley, #blessed_reviewers

Reviewed By: epriestley, #blessed_reviewers

Subscribers: epriestley, Korvin

Differential Revision: https://secure.phabricator.com/D9856