Show changes in task detail opens the compatibility pages app

Currently the show changes button in the task detail opens the old pages app.

Reproduce

1. Publish a page
2. Open the task in detail view (Assign to me - Preview task)
3. Click "Show changes" from the actionbar
4. The compatibility pages app opens

Expected
The preview should open the new pages app.

Actual
The compatibility pages app opens

Notes
Currently an action from the workflow compatibility module is being used which is hard coded for the compatibility pages app WorkItemLocalizedDiffAction.

I tried uninstalling the workflow compatibility module. When trying to click shows changes I end up with:

It seems we should be using WorkItemDiffAction for the show changes button. See MGNLWORKFLOW-384.