Provide imageUrl for ErrorBoundary test

flag=none

test plan:
  - Specs pass

qa risk: low

Change-Id: Id504544694127494ad53434d9a700bdb3ba1a75c
Reviewed-on: https://gerrit.instructure.com/c/canvas-lms/+/274422
Tested-by: Service Cloud Jenkins <svc.cloudjenkins@instructure.com>
Reviewed-by: Davis Hyer <dhyer@instructure.com>
QA-Review: Davis Hyer <dhyer@instructure.com>
Product-Review: Davis Hyer <dhyer@instructure.com>

jest/jest-setup.js

@@ -99,7 +99,6 @@ const ignoredErrors = [
   /The prop `hasLoaded` is marked as required in `HistoryList`/,
   /The prop `host` is marked as required in `CanvasContentTray`/,
   /The prop `id` is marked as required in `(CanvasSelectOption|ColHeader|DashboardCard|FormField|Option)`/,
-  /The prop `imageUrl` is marked as required in `GenericErrorPage`/,
   /The prop `isLiked` is marked as required in `Like`/,
   /The prop `isLoading` is marked as required in `LoadingWrapper`/,
   /The prop `jwt` is marked as required in `CanvasContentTray`/,

ui/shared/error-boundary/react/__tests__/index.test.js

@@ -33,7 +33,8 @@ class ThrowsErrorComponent extends React.Component {
 }
 
 const defaultGenericProps = {
-  errorCategory: '404'
+  errorCategory: '404',
+  imageUrl: 'http://imageUrl'
 }
 
 const defaultProps = () => ({