set max_attempts on SummaryMessageConsolidator job

if it fails, the periodic job will reschedule soon anyway, and we don't
want one bad shard backing everything up

Change-Id: I49bd2a9b0f3cd399deb2424e0382f8d54fd483ce
Reviewed-on: https://gerrit.instructure.com/31148
Reviewed-by: Rob Orton <rob@instructure.com>
Tested-by: Jenkins <jenkins@instructure.com>
Product-Review: Cody Cutrer <cody@instructure.com>
QA-Review: Cody Cutrer <cody@instructure.com>