to fix: ungroup_stats should be removed in favor of get_*_from_stats

[shajoezhu]

          to fix: ungroup_stats should be removed in favor of get_*_from_stats

Originally posted by @Melkiades in #1361 (comment)

[Melkiades]

@edelarua I think we are very close to complete this right?

[edelarua]

Yes! I believe this has now been removed from all analysis functions and the ungroup_stats() function can be removed.

[edelarua]

I can make a PR to delete the function. It's internal so shouldn't need any deprecation cycle.