[grid] Fixing failing test on GitHub

Author: diemol

java/server/test/org/openqa/selenium/grid/node/local/LocalNodeTest.java

@@ -182,6 +182,7 @@ public HttpResponse execute(HttpRequest req) {
       .add(caps, new TestSessionFactory(VerifyingHandler::new))
       .add(caps, new TestSessionFactory(VerifyingHandler::new))
       .add(caps, new TestSessionFactory(VerifyingHandler::new))
+      .maximumConcurrentSessions(2)
       .build();
 
     List<Callable<SessionId>> callables = new ArrayList<>();