20250515 snapshot packaged install missing /etc/zfs/ directory

From: <cyric_at_mm.st>
Date: Fri, 16 May 2025 06:19:57 UTC
After packaged installation using
FreeBSD-15.0-CURRENT-amd64-20250515-cb205f5ed808-277278-disc1.iso
snapshot, creating non-root zfs pools, and rebooting I noticed that
those pools are not imported.

The culprit here seems to be the /etc/zfs/ directory missing after
installation, so zpool.cache is not saved.  Creating it, importing the
non-root pool, and rebooting seems to fix the issue.