Adjust kasp tests to use 'checkds'

Adjust kasp tests to use 'checkds'

With 'checkds' replacing 'parent-registration-delay', the kasp
test needs the expected times to be adjusted. Also the system test
needs to call 'rndc dnssec -checkds' to progress the rollovers.

Since we pretend that the KSK is active as soon as the DS is
submitted (and parent registration delay is no longer applicable)
we can simplify the 'csk_rollover_predecessor_keytimes' function
to take only one "addtime" parameter.

This commit also slightly changes the 'check_dnssecstatus' function,
passing the zone as a parameter.