[issue][improve] zookeeper connections monitor data

[xiaotongwang1]

Fixes #9777

Motivation

The value of zookeeper_server_connections is incorrect when we open tls connection between client(broker、bookie) and zookeeper server

Modifications

when zkServer.getSecureServerCnxnFactory() not null ,will plus the connections and return

ServerCnxnFactory secCnxFactory = zkServer.getSecureServerCnxnFactory();
if (secCnxFactory != null) {
connections += secCnxFactory.getNumAliveConnections();
}

Verifying this change

This change is a trivial rework / code cleanup without any test coverage.

Does this pull request potentially affect one of the following parts:

If yes was chosen, please highlight the changes

• Dependencies (does it add or upgrade a dependency): (no)
• The public API: (no)
• The schema: (no)
• The default values of configurations:(no)
• The wire protocol: (no)
• The rest endpoints: (no)
• The admin cli options: (no)
• Anything that affects deployment: (no)

Documentation

• Does this pull request introduce a new feature?(no)

[merlimat]

This fix is fine, though since we have moved to ZK 3.6, we should drop the existing way of gathering the ZK metrics using AOP interceptors and instead enable the supported Prometheus metrics that ZK provides.

[xiaotongwang1]

@merlimat yes ,agree. I check the zookeeper state code ,it register a key with "num_alive_connections" ,and current AOP register a key with "zookeeper_server_connections",i think it can support export both 8000(current AOP style) and 7000 (zookeeper 3.6.x) next one or two release version ,then change the grafana template with num_alive_connections、watch_count、ephemerals_count..... and pulsar-zookeeper ZooKeeperStarter

============code of zookeeper 3.6.x=============
/**
* return the total number of client connections that are alive
* to this server
*/
public int getNumAliveConnections() {
int numAliveConnections = 0;

    if (serverCnxnFactory != null) {
        numAliveConnections += serverCnxnFactory.getNumAliveConnections();
    }

    if (secureServerCnxnFactory != null) {
        numAliveConnections += secureServerCnxnFactory.getNumAliveConnections();
    }

    return numAliveConnections;
}

[eolivelli]

LGTM

[eolivelli]

can you please merge with current master in order to pick up recent GH actions improvements ?

[Anonymitaet]

@xiaotongwang1 thanks for your code work. For this PR, do we need to update docs?

[xiaotongwang1]

@xiaotongwang1 thanks for your code work. For this PR, do we need to update docs?

No need to update.

[codelipenghui]

@xiaotongwang1 We have removed ZooKeeperServerAspect.java by #10533, I will close this issue first.