refs #7489
- as we are now using a different migration approach (knex-migrator), we don't need to remember the database version anymore
- it was once used to check the state of a database and based on it we decided to migrate or not
- with knex-migrator everything depends on the migration table entries and the current ghost version you are on
- on current master the leftover usage is to add the db version when exporting the database, which can be replaced by reading the ghost version
- removing this solves also an interesting migration case with knex-migrator:
- you are on 1.0
- you update to 1.1, but 1.1 has no migrations
- the db version would remain in 1.0
- because the db version was only updated when knex migrator executed a migration
