BENCH: put in np.random.seed on vbenches

[jreback]

all of the groupby vbenches need a np.random.seed(1234) to make them consistent from run-to-run (where they don't have them now).

Possibly should do this on other benches as well.

[hayd]

Could this just be stuck into pandas_vb_common ?

[jreback]

yes that should work
should remove any of the other ones
and test that it stays reasonably stable run to run

[jtratner]

👍

[RafalSkolasinski]

I am working on that now