Suggest results might be hidden behind a modal if SharePage does not exist

When using a picker with suggest.js on a modal, the proposed result might be just hidden behind the modal. This is particularly true in our integration tests executed in a minimal wiki where the SharePage does not exist.

The reason is that the z-index of the results div is lower to the z-index of the modal and SharePage does override this z-index in a style xobject to workaround this issue.
However, this issue should be fixed for all XS since it's a common UC.