conversations: fix clicking "all in" results

fixes CNVS-13326

test plan:
  * open conversations compose dialog
  * browse to a course group in the recipient finder
  * click the result for all students in the group
  * verify that the group is added as a recipient

Change-Id: I52e879d7c81af88ec31b11dbf4b58400849c0163
Reviewed-on: https://gerrit.instructure.com/35554
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Jake Sorce <jake@instructure.com>
Reviewed-by: Drew Bowman <dbowman@instructure.com>
QA-Review: Steven Shepherd <sshepherd@instructure.com>
Product-Review: Braden Anderson <banderson@instructure.com>