[JENKINS-75174] Allow webapp context configuration to be discovered v…

…ia Servlet 3.0 discovery (backport) (#903)

src/main/java/org/jvnet/hudson/test/JenkinsRule.java

@@ -942,7 +942,7 @@ protected ClassLoader configureClassLoader(ClassLoader loader) {
             }
         };
         context.setClassLoader(classLoader);
-        context.setConfigurations(new Configuration[]{new WebXmlConfiguration()});
+        context.setConfigurationDiscovered(true);
         context.addBean(new NoListenerConfiguration2(context));
         context.setServer(server);
         String compression = System.getProperty("jth.compression", "gzip");