crush: --show-utilization* implies --show-statistics

--show-utilization* outputs only if --show-statistics is set, which is
confusing. Instead of failing, set --show-statistics to avoid the
confusion.

Signed-off-by: Loic Dachary <loic@dachary.org>
crush: document the --test mode of operations

Signed-off-by: Loic Dachary <loic@dachary.org>
crush: remove scary message string

The string is no longer used and can be removed.

Signed-off-by: Loic Dachary <loic@dachary.org>