Refactor commit discussions to use DiscussionsActions concern

Summary

The Projects::CommitController currently has logic for handling discussions that could be consolidated by using the RapidDiffs::DiscussionActions concern introduced in !214069 (merged).

Current State

After adding the POST discussions endpoint using the RapidDiffs::DiscussionActions concern, there are opportunities to refactor existing code:

  1. The rapid_diffs_enabled? method is now available but not used in other parts of the controller
  2. The GET discussions endpoint could potentially leverage the concern as well

Proposed Changes

  • Refactor existing discussion-related code in Projects::CommitController to use the RapidDiffs::DiscussionActions concern
  • Move the GET discussions endpoint to use the concern for consistency

Related