keep shard ids consistent between spec blocks

otherwise connection pools won't reuse connections, and you'll run out

Change-Id: I66b6e0be125763cd623a91046ae3b74292dc8432
Reviewed-on: https://gerrit.instructure.com/30432
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Jacob Fugal <jacob@instructure.com>
Product-Review: Cody Cutrer <cody@instructure.com>
QA-Review: Cody Cutrer <cody@instructure.com>