Remove dead code from review_detail view on dvcs

Review Request #8285 — Created July 12, 2016 and submitted — Latest diff uploaded

Information

Review Board
dvcs
0d491ee...

Reviewers

In the review detail view, we are fetching all the DiffCommits on the
review request, organizating them according to their DiffSet and then
doing nothing with the result.

Verified the review detail view still works.