PERF: additonal GIL releasing
after #10199 (all of the groupbys)
these require slightly different templates as the object cannot have the `with nogil:`. These are all in `pandas/src/generate_code.py`

~~\- [ ] `groupby_count`~~
~~\- [ ] `is_monotonic`~~
- [ ] `take_1d`
- [ ] `take_2d`
- [ ] `take_2d_multi`
- [ ] `pad`
- [ ] `backfill`
- [x] `diff`
- [x] `join_indexer` (outer/inner/left)

in `algos.pyx`
- [x] `kthsmallest/kthlargest`
- [x] `group_median`
- [x] `roll_*` 
- [ ] drop_duplicates machinery
- [x] `nancorr`
