We "promote" v2 buckets to v3 if their measurements are out of order. This signals that their measurements are out of order and that optimizations that depend on the measurements being in order cannot be used.

If a bucket is marked as v3 but its measurements are in order, the only impact of this is that some optimizations are not used when reading from it. This isn't serious enough to warrant being a validation error; we also know that this is possible to hit (SERVER-116348).

We can make this check return a warning instead of an error.