fix async smoke test on liberty

instrumentation/liberty/liberty/javaagent/src/main/java/io/opentelemetry/javaagent/instrumentation/liberty/LibertyHttpServerTracer.java

@@ -23,6 +23,7 @@ public Context startSpan(HttpServletRequest request) {
 
   @Override
   protected Context customizeContext(Context context, HttpServletRequest httpServletRequest) {
+    context = super.customizeContext(context, httpServletRequest);
     return AppServerBridge.init(context);
   }