Prevent a race in the "inline" system test

Prevent a race in the "inline" system test

A short time window exists between logging the addition of an NSEC3PARAM
record to a zone and committing it to the current version of the zone
database.  If a query arrives during such a time window, an unsigned
response will be returned.  One of the checks in the "inline" system
test requires NSEC3 records to be present in an answer - that check
would fail in the case described above.  Use rndc instead of log
watching for checking whether zone signing and NSEC3 chain modifications
are complete in order to prevent intermittent "inline" system test
failures.

(cherry picked from commit e36c869e8511ab890ec63d8449f1aa29214ebd32)