Enable gitlab pages

Fixes #228 (closed) and supersedes !163 (closed). Enables easy resolving of #61 (closed).

The test page is online at https://test.archlinux.org/. Its project is here: https://gitlab.archlinux.org/svenstaro/pages-test/pages It uses the GitLab built-in Let's Encrypt integration.

Changes are already rolled out.

Upon inspection and merging, the reviewer must:

• Remove hetznerdns_record.gitlab_pages_test_* from archlinux.tf and run terraform apply
• Remove the project https://gitlab.archlinux.org/svenstaro/pages-test

host_vars/repro1.pkgbuild.com

@@ -6,7 +6,7 @@ ipv4_netmask: "/31"
 ipv6_address: "2604:1380:2001:4500::1"
 ipv6_netmask: "/127"
 ipv4_gateway: "147.75.81.78"
-ipv6_gateway: "2604:1380:2001:4500::2"
+ipv6_gateway: "2604:1380:2001:4500::"
 filesystem: "btrfs"
 network_interface: "enp1s0f0np0"
 system_disks: