Fix flaky AccessLoggerIntegrationTest (#5599)

Motivation:

`ServiceRequestContext` does not implement `equals()` which results in
an intermittent failure due to comparing instance references.

ref:
https://github.com/line/armeria/actions/runs/8655794720/job/23735309425?pr=5593#step:10:1210

Modifications:

- Compare the requestId instead

Result:

- Less flaky tests

---------

Co-authored-by: Trustin Lee <trustin@linecorp.com>

core/src/test/java/com/linecorp/armeria/server/logging/AccessLoggerIntegrationTest.java

@@ -17,6 +17,7 @@
 package com.linecorp.armeria.server.logging;
 
 import static org.assertj.core.api.Assertions.assertThat;
+import static org.awaitility.Awaitility.await;
 
 import java.util.concurrent.atomic.AtomicReference;
 
@@ -59,6 +60,7 @@ void testAccessLogger() throws Exception {
  assertThat(server.blockingWebClient().get("/").status().code()).isEqualTo(200);
  assertThat(server.requestContextCaptor().size()).isEqualTo(1);
  final ServiceRequestContext ctx = server.requestContextCaptor().poll();
- assertThat(CTX_REF).hasValue(ctx);
+ assertThat(ctx).isNotNull();
+ await().untilAsserted(() -> assertThat(CTX_REF).hasValue(ctx));
  }
 }