storage.postgresql: Use origin_visit_status.type value as source
This stops using the origin_visit.type as fallback values as now, the database has been migrated.
So this makes the origin_visit_status.type a not nullable column.
This also drops now redundant join instructions on origin_visit table when reading.
Related to swh/infra/sysadm-environment#2968 (closed)
Migrated from D5019 (view on Phabricator)