Review fixes for jetty-httpclient-12.0:testing (#18084)

Co-authored-by: otelbot <197425009+otelbot@users.noreply.github.com>

Author: otelbot[bot]

instrumentation/jetty-httpclient/jetty-httpclient-12.0/testing/src/main/java/io/opentelemetry/instrumentation/jetty/httpclient/v12_0/AbstractJettyClient12Test.java

@@ -115,15 +115,15 @@ public void sendRequestWithCallback(
   }
 
   @Test
-  void callbacksCalled() throws InterruptedException, ExecutionException {
+  void callbacksCalled() {
     URI uri = resolveAddress("/success");
     Request request = client.newRequest(uri).method("GET");
 
     CompletableFuture<Response> responseFuture = new CompletableFuture<>();
     TracingResponseListener responseListener = new TracingResponseListener(responseFuture);
 
     testing.runWithSpan("parent", () -> request.send(responseListener));
-    Response response = responseFuture.get();
+    Response response = responseFuture.join();
 
     assertThat(response.getStatus()).isEqualTo(200);
     testing.waitAndAssertTraces(