Problems with Secondary overload behavior

There are a couple of issues around our overload handling for secondaries.

- Secondaries that trigger an overload are stored as one `FormHistory` record, with the type `Labor Overload Form`. This means they don't show up in Labor History, which only looks for 'base' `FormHistory` entries so that it can group the additional forms together. I suspect this causes other problems as well.
- When the primary Labor Status Form is modified (or adjusted, probably) to fewer hours, removing the overload condition, we don't change the secondary away from an overload form, and we can't delete the overload's FormHistory record like we do for Primaries, because there is only one record for secondaries (see above)