R1:10db27833b6e

Remove old Phrequent propery rendering code and show "Time Spent" in higher precision

Summary:
See <https://discourse.phabricator-community.org/t/how-to-get-total-time-spent-on-a-task-in-minutes-or-hours/2241>.

Phrequent has two nearly-identical copies of its rendering code: one for old "property event" objects and one for newer "curtain" objects. In the upstream, both trackable object types (tasks and revisions) use curtains, so throw away the old code since it isn't reachable. Third-party trackable…