Major Description
This appears to be a side effect of this commit; by changing ClusterVerifier::RunKsck to call ksck->RunAndPrintResults instead of the list of individual ksck steps, not only is checksum_options_ effectively ignored, but the ksck run no longer does a checksum scan unless the test in question explicitly sets --checksum_scan.
ClusterVerifier is used in a lot of tests which presumably did care about checksumming the data, so we should probably restore it. At the very least, we should remove checksum_options_ since it's no longer in real use.