net/openldap24-server: Deprecate and set expiration date to 2022-12-31

Upstream is no longer supporting OpenLDAP 2.4 series; existing users
should migrate to a newer OpenLDAP release.

Reference: https://github.com/openldap/openldap.github.io/issues/2#issuecomment-1003778077
Reported by: Michael Osipov
PR: 267149