Use _assert_has_(no)_errors() in hacking tests
Use _assert_has_(no)_errors() in hacking tests

_assert_has_errors() and _assert_has_no_errors() us much easier to read
and understand. This change switches over the tests to use those fixture
methods.

Change-Id: I4aa8f973d1be34739a7fb2edcf85a956b2cf7859
Closes-Bug: #1512802

openstack/magnum,dimtruck/magnum,ArchiFleKs/magnum,openstack/magnum,ArchiFleKs/magnum,jay-lau/magnum,dimtruck/magnum