ITBLL should fail to start if misconfigured

The number of nodes in ITBLL must a multiple of width*wrap (defaults to 25M, but can be configured by adding two more args to the test invocation) or else verification will fail. This can be very expensive in terms of time or hourly billing for on demand test resources. Check the sanity of test parameters before launching any MR jobs and fail fast if invariants aren't met with an indication what parameter(s) need fixing.