Re-sync basic epic fields to work items

We re-queue the backfill migration because we backfill the data in
two steps:

1. The initial backfilling created a work item for every epic to
   unblock any follow-up migrations that  depend on the work item data.
   At the time we ran the migration, we did not sync epic to work item
   data by default in the application layer.

2. The second backfilling (this one) re-syncs the data again to make
   sure it's up to date. At this time we enabled syncing epic to work
   item data already by default.

Changelog: changed