Only honour singleton-ness on interceptor, not JUnit runner

core/deployment/src/main/java/io/quarkus/deployment/dev/testing/JunitTestRunner.java

@@ -779,6 +779,7 @@ private DiscoveryResult discoverTestClasses() {
         // TODO this seems logical, but DOES NOT makes integration-test/test-extension/tests fail
         ClassLoader parent = ClassLoader.getSystemClassLoader();
         System.out.println("HOLLY using parent for facade loader " + parent);
+        FacadeClassLoader.clearSingleton();
         FacadeClassLoader facadeClassLoader = FacadeClassLoader.instance(parent); // TODO ideally it would be in a different module, but that is hard CollaboratingClassLoader.construct(parent);
 
         facadeClassLoader.setAuxiliaryApplication(true);

core/deployment/src/main/java/io/quarkus/test/junit/classloading/FacadeClassLoader.java

@@ -95,6 +95,10 @@ public class FacadeClassLoader extends ClassLoader implements Closeable {
 
     private static volatile FacadeClassLoader instance;
 
+    public static void clearSingleton() {
+        instance = null;
+    }
+
     // TODO does it make sense to have a parent here when it is sometimes ignored?
     // We don't ever want more than one FacadeClassLoader active, especially since config gets initialised on it.
     // The gradle test execution can make more than one, perhaps because of its threading model.