BUG: Mixed DataFrame with Extension Array incorrect aggregation
- [ ] closes #34520 by reverting #32950

cc @jbrockmendel  ping @jbrockmendel  I think there are better fixes available.  The underlying problem is that we're calling `nanops.nansum` on an IntegerArray and that raises `ValueError`.  So we should either make `nanops.nansum` handle `IntegerArray` or change the definition of `f` to dispatch to `EA._reduce` cc @jorisvandenbossche has been working on the latter approach closing in favour of #32867