Put older milestones back on the left

Summary:
This reverts commit 3f50ba90f1d0d30008ea13457dd90f8ea83f25b7.

Fixes T10412. Everyone seems to hate this and I don't feel strongly about it. It's definitely a little weird.

Test Plan: Straight revert.

Reviewers: chad

Reviewed By: chad

Maniphest Tasks: T10412

Differential Revision: https://secure.phabricator.com/D15644