Avoid duplicated logging when RHBQ is tested on RHEL

quarkus-test-core/src/main/java/io/quarkus/test/logging/Log.java

@@ -11,6 +11,7 @@
 import java.util.Map;
 import java.util.Objects;
 import java.util.Random;
+import java.util.logging.Handler;
 import java.util.logging.Level;
 import java.util.logging.LogManager;
 import java.util.logging.Logger;
@@ -20,6 +21,7 @@
 import org.jboss.logmanager.handlers.ConsoleHandler;
 import org.jboss.logmanager.handlers.FileHandler;
 
+import io.quarkus.bootstrap.logging.QuarkusDelayedHandler;
 import io.quarkus.test.bootstrap.QuarkusScenarioBootstrap;
 import io.quarkus.test.bootstrap.ScenarioContext;
 import io.quarkus.test.bootstrap.Service;
@@ -105,6 +107,17 @@ public static void configure(ScenarioContext scenario) {
         Logger logger = LogManager.getLogManager().getLogger("");
         logger.setLevel(level);
 
+        // Remove existing handlers
+        for (Handler handler : logger.getHandlers()) {
+            // we don't need QuarkusDelayedHandler,
+            // and it leads to log duplication when the 'java.util.logging.manager'
+            // system property is set to the 'org.jboss.logmanager.LogManager'
+            if (handler instanceof QuarkusDelayedHandler) {
+                logger.removeHandler(handler);
+                break;
+            }
+        }
+
         // - Console
         ConsoleHandler console = new ConsoleHandler(
                 ConsoleHandler.Target.SYSTEM_OUT,