add delayed_jobs_shard to DefaultShard

Change-Id: Iee742e19c2c87b914b4d2e5bc8994cd6ea2527fc
Reviewed-on: https://gerrit.instructure.com/29951
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Cody Cutrer <cody@instructure.com>
Product-Review: James Williams  <jamesw@instructure.com>
QA-Review: James Williams  <jamesw@instructure.com>