change SIS App token name in Canvas

fixes SIS-698

Test plan:
- confirm it's changed

Change-Id: Idba02da519ecc4270c1dc53b008b9a565c899f7c
Reviewed-on: https://gerrit.instructure.com/45142
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Duane Johnson <duane@instructure.com>
Product-Review: Cosme Salazar <cosme@instructure.com>
QA-Review: Jeremy Putnam <jeremyp@instructure.com>