fix quiz statistics feature flag spec

fixes CNVS-15528

Change-Id: I6f0dfebf0e94d60b52e5bd6556cb7b1fe72bab87
Reviewed-on: https://gerrit.instructure.com/41255
Reviewed-by: Rob Orton <rob@instructure.com>
Product-Review: Bryan Madsen <bryan@instructure.com>
QA-Review: Bryan Madsen <bryan@instructure.com>
Tested-by: Jenkins <jenkins@instructure.com>