user.communication_channel doesn't return retired channels

CNVS-10780

test plan
- create two email communication channels
- verify that the primary channel has default preferences
- verify that the other channel has all preferences set to never
- retired the primary channel
- ensure that the other channel now has default preferences set

Change-Id: I14de93894864dac5353c815235932680b8151b2c
Reviewed-on: https://gerrit.instructure.com/29378
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Braden Anderson <banderson@instructure.com>
QA-Review: Steven Shepherd <sshepherd@instructure.com>
Product-Review: Joel Hough <joel@instructure.com>