Add testing for slave Host Controller join to domain testsuite DefaultConfigSmokeTestCase

DefaultConfigSmokeTestCase tests the "domain.xml + host.xml" config set, so a master running servers is tested. But "domain.xml + host-master.xml" is not tested nor is "host-slave.xml". These latter two can be tested in combination, and that closes the whole where we aren't testing a slave joining a domain configured to use our default configs.