[dagit] Lazy-load partition set info for Schedules
We currently load a ton of data for partition sets when viewing schedules, including in the "Instance status" page view of all schedules on the instance. This can be really slow, and blocks the entire query.
Separate loading partition set data into lazy subqueries that can be triggered by request from the user.
View /instance/schedules. Verify that the "Partition status" column has links that allow lazy-loading the partition set data. Click, verify proper loading/loaded behavior.
Verify same on Schedule permalink details.
Reviewers: bengotow, prha, alangenfeld
Reviewed By: bengotow
Differential Revision: https://dagster.phacility.com/D9202