Repairs the limited request tests according to the patch in commit a3dd3072

Notes:
 - To do: if the zone cut is deduced from a RRSIG record, we could also detect if
   there was a wildcard match and set the RRL_WILDCARD flag.
 - Perhaps only the name needs to be retrieved from the SOA record in case of
   a NXDOMAIN, since RRL will use the query name anyway for the other classifications.

The RRL rate is measured and averaged over a period of time. This
measurement window was applied only for existing buckets. This change
enables this behavior for new buckets as well.

This should have no operational impact. But it will make our testing
a bit easier.