uma: Use LIFO for non-SMR bucket caches

When SMR was introduced, zone_put_bucket() was changed to always place
full buckets at the end of the queue. However, it is generally
preferable to use recently used buckets since their items are more
likely to be resident in cache. So, for buckets that have no constraint
on item reuse, use a last-in-first-out ordering as we did before.

Reviewed by: rlibby
Tested by: dhw, glebius
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D26426