Point the SSH host sign policy at the role that exists

The sshca mount only defines the signhost role, so the policy grant for
sshca/sign/host never matched a real path and every host-key signing
request from the Puppet compilers was denied. The role also excluded
unkin.net, rejecting the git.unkin.net and grafana.unkin.net principals
the manifest sends.

- Grant sshca/sign/signhost instead of sshca/sign/host
- Add unkin.net to the signhost role's allowed_domains

config/ssh_secret_backend_role/sshca/signhost.yaml

@@ -3,6 +3,6 @@ algorithm_signer: rsa-sha2-256
 ttl: 315360000  # 87600 * 3600
 allow_host_certificates: true
 allow_user_certificates: false
-allowed_domains: "main.unkin.net,consul"
+allowed_domains: "unkin.net,main.unkin.net,consul"
 allow_subdomains: true
 allow_bare_domains: false

policies/sshca/sign/host.yaml

@@ -1,7 +1,7 @@
 # Allow signing SSH host certificates
 ---
 rules:
-  - path: "sshca/sign/host"
+  - path: "sshca/sign/signhost"
     capabilities:
       - create
       - update