Don't show closed changes in the open list

This makes the unreviewed/open change list a little more consistent
but makes it impossible to view closed changes.  We'll add that back
later in another manner, but for now, focus the review task lists
on open changes.

Change-Id: Ide7027e25df40800cde7cba224129f14d2745775
Merge "Don't show closed changes in the open list"