storage: Stop accessing the db attribute directly
This puts the indexer storage in line with swh.storage when swh-storage!77 (closed) is applied.
Test Plan
unsurprisingly, make test still works
Migrated from D328 (view on Phabricator)
This puts the indexer storage in line with swh.storage when swh-storage!77 (closed) is applied.
unsurprisingly, make test still works
Migrated from D328 (view on Phabricator)