net-mgmt/nagios-pf-plugin: broken on FreeBSD 15, deprecate

This port requires the obsolete ioctl(DIOCGETSTATUS), which is no
longer supported on FreeBSD 15. Upstream is dead, so deprecate.
It also has some questionable warnings.

See also: D41651
MFH: 2026Q1

(cherry picked from commit bd7e3e8a36c48d6a31b8560c39b8ef033e6caa99)