MINOR: add removed controller metrics to zk2kraft

[FrankYang0529]

Followup: #18573 (review)

Add following removed controller metrics to zk2kraft.html.

• kafka.controller:type=ControllerChannelManager
• kafka.controller:type=ControllerEventManager
• kafka.controller:type=KafkaController
• kafka.controller:type=ControllerStats

Committer Checklist (excluded from commit message)

• Verify design and implementation
• Verify test coverage and CI build status
• Verify documentation (including upgrade notes)

[chia7712]

This description is not accurate. We don't need to explain the all usage of those metrics, since that is not the purpose of this docs. Maybe we can add those metrics to the line#161? WDYT?

[FrankYang0529]

Agree. I think we should also update description at line#158.

[chia7712]

Should we list complete metrics attributes? It would be useful to search specific metrics. WDYT?

[chia7712]

#18658 add complete metrics, so I think PR should follow that pattern too.

[FrankYang0529]

I will follow it. Thanks.

[FrankYang0529]

Updated it. Thanks.

[chia7712]

Should we merge all metrics item into single one?

[chia7712]

there are three listed items for now

[chia7712]

@FrankYang0529 could you please merge the following metrics?

        <li>
            <p>
                Remove the metrics which is monitoring the number of Zookeeper migrations.
            </p>
            <ul>
                <li><code>kafka.controller:type=KafkaController,name=MigratingZkBrokerCount</code></li>
                <li><code>kafka.controller:type=KafkaController,name=ZkMigrationState</code></li>
            </ul>
            <p>
                Kafka remove all zookeeper dependencies, so the metrics is removed.
            </p>
        </li>
        <li>
            <p>
                Remove the metrics which is monitoring requests waiting in the topic purgatory
            </p>
            <ul>
                <li><code>kafka.server:type=DelayedOperationPurgatory,name=PurgatorySize,delayedOperation=topic</code></li>
                <li><code>kafka.server:type=DelayedOperationPurgatory,name=NumDelayedOperations,delayedOperation=topic</code></li>
            </ul>
            <p>
                In Kraft mode, Zookeeper is not used, so the metrics is removed.
            </p>
        </li>

[chia7712]

For another, it would be great to attach the screenshot of web page

[FrankYang0529]

Thanks for the suggestion. Updated it.