devel/elixir-{hex,make}: remove ports that are now user-installed

[dch]

Summary

Recent versions of these devel ports are now designed to be installed
per-user, not system-wide.

Sponsored by: SkunkWerks, GmbH

[dch]

committed in https://cgit.freebsd.org/ports/commit/?id=c613b7f7c133