Hmm, there's a possibility of overwriting people's new settings if this migration is ever executed more than once, or if we apply it now after we've already manually migrated people's data. If someone has already set their axis settings to `scatter` (which didn't exist before) in the new schema, running this migration will reset it to `line` or `stacked`. So we probably shouldn't execute this migration at all and just remove the old `stacked` field?