pyrocufflink-dns: Drop group

The internal DNS server for the *pyrocufflink.blue* et al. domains runs
on the firewall now, and is thus no longer managed by Ansible.  Dropping
the group variables so the file encrypted with Ansible Vault can go
away.

ci/pyrocufflink-dns.jenkinsfile

@@ -1,13 +0,0 @@
-@Library('cfgpol')_
-
-applyConfigPolicy(
-    'pyrocufflink-dns',
-    [
-        'ProtonVPN': [
-            'protonvpn.yml',
-        ],
-        'BIND': [
-            'named-server.yml',
-        ],
-    ],
-)