generate_resmoke_tasks doesn't apply max_sub_suites option

When max_sub_suites is set for a given suite, generate_resmoke_tasks does not actual apply it to split up the suites. See here

As a Server engineer,
I want max_sub_suites to control how much resmoke suites are split up
so that I have a way to prevent suites being split up too much.

AC:

• A generated suite with max_sub_suites set should only be split into the specified number of sub-suites.