tune_sssd.sh: disable rdns (conflicts with incorrect lines in /etc/hosts)

dc-client/tune_sssd.sh

@@ -48,8 +48,10 @@ cat <<EOF >/etc/krb5.conf.d/ad
 [libdefaults]
  dns_lookup_kdc = true
  dns_lookup_realm = true
- rdns = true
+ rdns = false
 EOF
+# rdns disabled!
+# See https://bugs.etersoft.ru/show_bug.cgi?id=15473#c13
         ;;
     *)
         fatal "Unsupported distro $(epm print info -d)"