fix course settings "hide totals" setting

test plan:
* should be able to set the "Hide totals in
student grades summary" in course settings
and save properly

(side bonus: it should stay disabled while reloading)

closes #CNVS-17329

Change-Id: I3150654bf0b17a143c1ca8af004af9823aad731d
Reviewed-on: https://gerrit.instructure.com/45487
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Dan Minkevitch <dan@instructure.com>
QA-Review: Jahnavi Yetukuri <jyetukuri@instructure.com>
Product-Review: James Williams  <jamesw@instructure.com>