Optionally skip zil_close during zvol_create_minor_impl

If there were no zil entries to replay, skip zil_close. zil_close waits
for a transaction to sync. That can take several seconds, for example
during pool import of a resilvering pool. Skipping zil_close can cut
the time for "zpool import" from 2 hours to 45 seconds on a resilvering
pool with a thousand zvols.

Reviewed-by: Richard Yao <richard.yao@alumni.stonybrook.edu>
Reviewed-by: Alexander Motin <mav@FreeBSD.org>
Reviewed-by: Ryan Moeller <ryan@iXsystems.com>
Sponsored-by: Axcient
Closes #13999
Closes #14015