fix account notification roles for cross-shard users

test plan:
* account notifications should not break the dashboard
 for users located on other shards

closes #CNVS-17639

Change-Id: Ie350c4832f7a5a4c9e88a83674f41a41a1c04874
Reviewed-on: https://gerrit.instructure.com/46346
Tested-by: Jenkins <jenkins@instructure.com>
Product-Review: Jeremy Stanley <jeremy@instructure.com>
Reviewed-by: Jeremy Stanley <jeremy@instructure.com>
QA-Review: Clare Strong <clare@instructure.com>