These are only used during mission generation. Remove them from the save
state to reduce compatibility requirements. We also have at least one
report of this data being corrupted... somehow. I don't know how that
could have happened, but if there's no data to corrupt in the first
place that's not a problem. If the corruption _does_ recur, it'll be
much easier to repro if it corrupts during mission generation rather
than during turn initialization.
Fixes https://github.com/dcs-liberation/dcs_liberation/issues/2729.