Show DNSSEC status in soa list, also deactivation

In #6450 (closed) I added an icon in the soa list to show if dnssec is active.

However I used the dnssec_initialized value, which does not get reset when it's deactivated. (note: only for bind, powerdns always removed the keys when deactivating...thus dnssec_initialized is turned off there).

I propose to add an additional check for dnssec_wanted.