Stop batch comment actions showing on commit discussions

Merged Phil Hughes requested to merge batch-comments-commit-comment into master

What does this MR do?

This hides the batch comment actions on commit discussions. Commit discussions are not part of merge requests so we don't support reviews on these discussions.

What are the relevant issue numbers?

Closes https://gitlab.com/gitlab-org/gitlab-ee/issues/8052

Does this MR meet the acceptance criteria?