Increase zone load timeout in the "rndc" test
requested to merge 2115-the-load-of-huge-zone-can-take-over-100-secs-when-running-under-a-sanitiser-v9_16 into v9_16
The "huge.zone" zone can take longer than 100 seconds to load when running under a sanitizer. Increase the relevant zone load timeout to prevent intermittent failures of the "rndc" system test.
(cherry picked from commit fd08918d)
Closes #2115 (closed)