Fix LTI 2 group service endpoint
Fix LTI 2 group service endpoint

Closes INTEROP-6281

Test Plan:
In a rails console, verify that
Lti::UsersApiController::SERVICE_DEFINITIONS.last
now has an endpoint property that is set to
"api/lti/groups/{group_id}/users"

Note:
The service definition constants in LTI 2
servicve controllers are used to manually
construct tool consmumer profiles for
LTI 2 users that leverage the plagiarism
detection platform

Change-Id: Id85144cd9e831646ee55e13a43c52fa68512deda
Reviewed-on: https://gerrit.instructure.com/c/canvas-lms/+/250541
Tested-by: Service Cloud Jenkins <9144042a601061f88f1e1d7a1753ea3e2972119d@instructure.com>
Reviewed-by: Mysti Lilla <431d062aff1e8f25416b3a7b732fe6effdb03f9a@instructure.com>
QA-Review: Mysti Lilla <431d062aff1e8f25416b3a7b732fe6effdb03f9a@instructure.com>
Product-Review: Weston Dransfield <e9203059795dc94e28a8831c65eb7869e818825e@instructure.com>

sfu/canvas-lms,sfu/canvas-lms,instructure/canvas-lms,instructure/canvas-lms,instructure/canvas-lms,instructure/canvas-lms,sfu/canvas-lms,instructure/canvas-lms,instructure/canvas-lms,sfu/canvas-lms,instructure/canvas-lms,sfu/canvas-lms,sfu/canvas-lms,sfu/canvas-lms