Previously, HornetQ and Artemis tests were using a test configuration
class listing the configuration classes to use explicitly in the purpose
of disabling the XA support.

This had a very unfortunate side effect for Artemis as we forgot to add
an import on the "real" configuration and this got unnoticed because of
this duplication.

It turns out that this special configuration class is no longer necessary
as XA backs off automatically anyway now. The tests have been updated
to use the regular auto-configuration and were failing with Artemis. The
import has now be added.

Closes gh-4226