Unmute RestClientMultipleHostsIntegTests.testCancelAsyncRequests

The underlying issue is closed, so either this test should be running correctly
now, is still failing for valid reasons or can be removed. Either way we need to
enable it to see.

client/rest/src/test/java/org/elasticsearch/client/RestClientMultipleHostsIntegTests.java

@@ -258,7 +258,6 @@ public void onFailure(Exception exception) {
         }
     }
 
-    @Ignore("https://github.com/elastic/elasticsearch/issues/45577")
     public void testCancelAsyncRequests() throws Exception {
         int numRequests = randomIntBetween(5, 20);
         final List<Response> responses = new CopyOnWriteArrayList<>();