Add a statschannel test case for DNSSEC sign metrics that has more
keys than there are allocated stats counters for. This will produce
gibberish, but at least it should not crash.
(cherry picked from commit 31e8b2b13c)
In addition to gather how many times signatures are created per
key in a zone, also count how many of those signature creations are
because of DNSSEC maintenance. These maintenance counters are
incremented if a signature is refreshed (but the RRset did not
changed), when the DNSKEY RRset is changed, and when that leads
to additional RRset / RRSIG updates (for example SOA, NSEC).
This adds tests to the statschannel system test for testing if
the dnskey sign operation counters are incremented correctly.
It tests three cases:
1. A zone maintenance event where all the signatures that are about
to expire are resigned.
2. A dynamic update event where the new RR and other relevant records
(SOA, NSEC) are resigned.
3. Adding a standby key, that means the DNSKEY and SOA RRset are
resigned.
