refs PLAT-4821
* update will not contain the whole subscription
test plan:
* with the live events LTI tool installed and running (see the docs),
update a subscription (eg, mark it deleted)
* this endpoint should succeed even though `ContextType` isn't present
in the request
Change-Id: I0773f18d5a2793c1248b4c761dc5bd79c03537a0
Reviewed-on: https://gerrit.instructure.com/208721
Tested-by: Jenkins
Reviewed-by: Marc Phillips <mphillips@instructure.com>
QA-Review: Marc Phillips <mphillips@instructure.com>
Product-Review: Xander Moffatt <xmoffatt@instructure.com>