DYNDNS: dyndns_update is not enough
When dyndns_update is set to True and dyndns_refresh_interval is
not set or set to 0, DNS is not updated at all.
With this patch DNS is updated when sssd changes its state to
online.
If dyndns_refresh_interval is set, updates are performed as
before - i. e. when comming online and then every
dyndns_refresh_interval.
Resolves:
https://pagure.io/SSSD/sssd/issue/4047
Reviewed-by: Pavel Březina <pbrezina@redhat.com>