sysutils/beadm-devel: Deprecate and set expiration date to 2024-08-15

This port (sysutils/beadm-devel) has not been updated in years and the
corresponding main port (sysutils/beadm) is known to be stable.

PR: 280189
Approved by: tcberner (mentor), [email protected] (maintainer)
Differential Revision: https://reviews.freebsd.org/D45977