be tolerant of a missing shard for job timing hook

refs CNVS-16467

Change-Id: I2e809ae9ed3eaddc5e33f38ed860be71a95aa094
Reviewed-on: https://gerrit.instructure.com/46306
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Rob Orton <rob@instructure.com>
Product-Review: Cody Cutrer <cody@instructure.com>
QA-Review: Cody Cutrer <cody@instructure.com>