Segment stats are currently inconsistent when it comes to (soft-)deletes. The number of deletes are counted in a different way for non-searchable committed segment infos than for searchable ones, e.g. soft-deletes are not treated as deletes in committed segment infos.

We should make sure to have segment infos record the number of soft deletes as well, so that we return consistent numbers, and preferably also return information regarding the count of soft-deletes vs hard-deletes in the API.