Avoid find -s, use find | sort instead.

find -s was introduced to make the metalog more
deterministic. However, find -s is not portable. find | sort is
portable and accomplishes the same goals, even if it isn't
pedantically the same. TZS is the same before / after the change so
any fussy differences between the two are moot and there won't be
METALOG churn across this change.

Differential Revision: https://reviews.freebsd.org/D14231