TestAuthenticationFramework should not extend TestMiniSolrCloudCluster

TestAuthenticationFramework should not extend TestMiniSolrCloudCluster. The TestMiniSolrCloudCluster is actually a test for MiniSolrCloudCluster and not a generic test framework class. I saw a local failure for TestAuthenticationFramework.testSegmentTerminateEarly which should never be executed in the first place.