tf-stage1/archlinux: Move luna domainkey to the lists.al.org subdomain

luna uses the luna domainkey now, instaed of the luna2 domainkey. The list (hosted on luna) also use lists.archlinux.org for all ml now[1].

[1] https://lists.archlinux.org/pipermail/arch-dev-public/2020-December/030248.html

approved this merge request

merged

mentioned in commit 040595fe