rename student outcomes gradebook feature

fixes CNVS-12951

test plan:

- navigate to the feature options
- student outcomes gradebook should be renamed
  student learning mastery gradebook

Change-Id: I86befc44097e1053eb52e7c6b7ae8fa1d2bd3cba
Reviewed-on: https://gerrit.instructure.com/36265
Reviewed-by: Braden Anderson <braden@instructure.com>
Tested-by: Jenkins <jenkins@instructure.com>
QA-Review: Trevor deHaan <tdehaan@instructure.com>
Product-Review: Drew Bowman <dbowman@instructure.com>