fix uncaught TypeError in k5 tests

If no mocks are provided, the accounts break when sorting by name

test plan:
  - run `yarn test:jest ui/features/k5_dashboard/react/__tests__/CreateCourseModal.test.js`
    - notice somewhat clean test logs
  - remove the change
  - rerun `yarn test:jest ui/features/k5_dashboard/react/__tests__/CreateCourseModal.test.js`
    - notice :barf: of red

qa risk: low

Change-Id: I7286ae6cc0bc4ba0ad75929f232cfbf7186e2eae
Reviewed-on: https://gerrit.instructure.com/c/canvas-lms/+/273943
Tested-by: Service Cloud Jenkins <[email protected]>
Reviewed-by: Omar Soto-Fortuño <[email protected]>
QA-Review: Omar Soto-Fortuño <[email protected]>
Product-Review: Omar Soto-Fortuño <[email protected]>

ui/features/k5_dashboard/react/__tests__/CreateCourseModal.test.js

@@ -86,6 +86,7 @@ describe('CreateCourseModal', () => {
   })
 
   it('shows a spinner with correct title while loading accounts', async () => {
+    fetchMock.get(MANAGEABLE_COURSES_URL, MANAGEABLE_COURSES)
     const {getByText} = render(<CreateCourseModal {...getProps()} />)
     await waitFor(() => expect(getByText('Loading accounts...')).toBeInTheDocument())
   })