ZOOKEEPER-4749: Respect zookeeper.request.timeout also for asynchronous api

[kezhuw]

Currently, zookeeper.request.timeout is only respected in synchronous api. I think there are should be no much differences between following two.

String createdPath = zk.create("/path", data, Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);

CompletableFuture<String> future = new CompletableFuture<>();
zk.create("/path", data, Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT, (rc, path, ctx, name) -> {
    if (rc == 0) {
        future.complete(name);
    } else {
        future.completeExceptionally(KeeperException.create(KeeperException.Code.get(rc), path));
    }
}, null);
String createdPath = future.join();

After this pr, we are able to unify synchronous api through calls to asynchronous api as review comments pointed out if we feel there are too much identical code between synchronous and asynchronous api.

[kezhuw]

After read ZOOKEEPER-2251. I think we were introducing a feature to solve/circumvent a not reproduced bug.

• zookeeper.request.timeout is somewhat similar to connectTimeout.
• The stack show that packet was not notified or finished.

I did not find matching git tag for that stack dump.

[kezhuw]

This does not guarantee Code.REQUESTTIMEOUT in returning as sendThread.cleanAndNotifyState() will reset r.err to Code.CONNECTIONLOSS. The old testing code is cheating us as it modified client side behavior.