Update the autosign system test with new expected behavior.
The 'nozsk.example' zone should have its expired zone signatures
deleted and replaced with signatures generated with the KSK.
The 'inaczsk.example' zone should have its expired zone signatures
deleted and replaced with signatures generated with the KSK.
In both scenarios, signatures are deleted, not retained, so the
"retaining signatures" warning should not be logged.
Furthermore, thsi commit fixex a test bug where the 'awk' command
always returned 0.
Finally, this commit adds a test case for an offline KSK, for the zone
'noksk.example'. In this case the expired signatures should be retained
(despite the zone being bogus, but resigning the DNSKEY RRset with the
ZSK won't help here).
(cherry picked from commit fbd559ad0d)
17ae663084