dns: fqdn only needs domain string

This is from the caas days, when we had hyphenated subdomains flag

src/directoryserver.js

@@ -312,7 +312,7 @@ async function start() {
     };
 
     const domainObject = await domains.get(settings.dashboardDomain());
-    const dashboardFqdn = dns.fqdn(constants.DASHBOARD_SUBDOMAIN, domainObject);
+    const dashboardFqdn = dns.fqdn(constants.DASHBOARD_SUBDOMAIN, settings.dashboardDomain());
     const certificatePath = await reverseProxy.getCertificatePath(dashboardFqdn, domainObject.domain);
 
     gServer = ldap.createServer({