AbstractModelIntegrationTest: fix of NPE on dummyAuditService

DummyAuditService is not a managed component, so we can safely init
it in constructor and then we don't have to check its nullity.
NPE happened in TestLoggingConfiguration test that (for good reasons)
didn't call super.initSystem().

model/model-test/src/main/java/com/evolveum/midpoint/model/test/AbstractModelIntegrationTest.java

@@ -203,15 +203,14 @@ public abstract class AbstractModelIntegrationTest extends AbstractIntegrationTe
     protected boolean verbose = false;
 
     public AbstractModelIntegrationTest() {
-        super();
+        dummyAuditService = DummyAuditService.getInstance();
     }
 
     @Override
     public void initSystem(Task initTask, OperationResult initResult) throws Exception {
         logger.trace("initSystem");
         dummyResourceCollection = new DummyResourceCollection(modelService);
         startResources();
-        dummyAuditService = DummyAuditService.getInstance();
         InternalsConfig.reset();
         InternalsConfig.setAvoidLoggingChange(isAvoidLoggingChange());
         // Make sure the checks are turned on