[improve][broker]PIP-333 Add monitor metrics for the number of connections to client IPs and roles

[yyj8]

For detailed improvement instructions, please refer to issues：
apache#21934

Motivation

Currently, Pulsar does not monitor the number of connections to client IPs and roles. When there are many business teams accessing the cluster, and there are also many topics and production consumers, it is difficult for us to quickly locate which IPs or roles are accessing the cluster abnormally from a global perspective and optimize them. So, we hope to have a monitoring indicator that can statistically analyze the connection information between IP and role dimensions, making it easier to quickly locate problems in the later stage.

Modifications

Add new metircs to ServerCnx.java class:

    private static final Gauge clientIpAndRoleConnections = Gauge.build()
            .name("pulsar_broker_client_ip_role_connections")
            .labelNames("ip", "role")
            .help("The number of client IP and role connections")
            .register();

Documentation

• doc
• doc-required
• doc-not-needed
• doc-complete

Matching PR in forked repository

PR in forked repository: #7