don't use testcluster.yml in canvas-lms

also enable quiz statistics feature flag in open source

Change-Id: I89d43d2e114a51330c7eca7e930291fa5bf5c759
Reviewed-on: https://gerrit.instructure.com/40907
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Nick Cloward <ncloward@instructure.com>
Product-Review: Cody Cutrer <cody@instructure.com>
QA-Review: Cody Cutrer <cody@instructure.com>