Use strict metadata reads during migration selection so a metadata bucket with a
missing metadata/dbp key is not interpreted as the latest DB version.
Recover this state from mandatory DB version 33, the last mandatory version
before the v0.20.x releases that could initialize a DB without writing the DB
version key. This runs migration 35 without replaying migrations 0 through 33
against a DB that was already created by a modern schema/code path.
After the selected migrations complete, syncVersions writes the latest DB
version as usual.
