R1:130aa755bb0e

Exclude closed tasks from blocked/blocking filter

Summary: Fixes T7392. When filtering blocked/blocking Maniphest tasks, don't consider closed tasks.

Test Plan:
# Created `T1` and `T2` with `T2 depends on T1`.
# Marked `T1` as resolved.
# Searched for tasks "blocked by other tasks" and noted that `T2` wasn't in the result set.

Reviewers: btrahan, #blessed_reviewers, epriestley

Reviewed By: #blessed_reviewers, epriestley

Subscribers: Korvin, epriestley

Maniphest Tasks: T7392

Differential Revision…