Summary:
Intgration tests don't currently have a lot of splits going on while there is IO.
This changes that by changing the split aglorithm and the max region hfile size. That should make things split more.
Additionally this allows ITBLL to start with just one region if hbase.test.pre-split-table is False.
Test Plan: Test on a cluster with ITBLL slow determinitic monkey and stress am monkey.
Differential Revision: https://reviews.facebook.net/D44181
8019009563