CLN: removes BinGrouper kind of cython methods
prob the most lines removed at one time!

can you do an asv run and see if any anomalies.

you can kill that bin grouper test (that you are now skipping) as well.
 I checked with vbench and benchmarks were stable. [this line](https://github.com/pydata/pandas/pull/10976/files#diff-720d374f1a709d0075a1f0a02445cd65R1799) is the only added overhead which is pretty efficient
 gr8 thanks!
 Very nice! I was wondering why we had all these binned groupby routines in Cython.
