ensure ExternalFeedAggregator doesn't choke through pgbouncer

refs CNVS-15875

Change-Id: I2ac0b7ddf350b08486ad0ea4cf03e3715cc1f39a
Reviewed-on: https://gerrit.instructure.com/43182
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>