freebsd-update: create deep BEs by default

The -r flag to bectl needs to go away, and we need to just do the right
thing. In the meantime, we can apply an -r in freebsd-update as a
minimal fix to stop creating partial backups in these (non-default) deep
BE setups.

PR: 267535
(cherry picked from commit 989c5f6da99081b1f2b76ec09e91078e531e1250)
(cherry picked from commit 80f747781f125576de40ab8b3d8d70b351ef0518)

Approved by: so
Security: FreeBSD-EN-23:13