Replace manual mock data with graphql fixtures in on-call schedules
As suggested in !90497 (comment 1020229508)
Tests within ee/spec/frontend/oncall_schedule use manually mocked data, these should be replaced with graphql fixtures
As suggested in !90497 (comment 1020229508)
Tests within ee/spec/frontend/oncall_schedule use manually mocked data, these should be replaced with graphql fixtures