TestLiveServer: remove xfail with test_item
TestLiveServer: remove xfail with test_item

The `live_server` fixture is expected to auto-use/-inject the
`transactional_db` fixture, via `_live_server_helper`.

thedrow/pytest-django,tomviner/pytest-django,hoh/pytest-django,pelme/pytest-django,bforchhammer/pytest-django,aptivate/pytest-django,ojake/pytest-django,reincubate/pytest-django,davidszotten/pytest-django,felixonmars/pytest-django,ktosiek/pytest-django,pombredanne/pytest_django,RonnyPfannschmidt/pytest_django