[feat][broker] PIP-264: Add OpenTelemetry broker connection metrics

[dragosvictor]

PIP-264

Motivation

Adds broker connection metrics to the OpenTelemetry pipeline.

Modifications

• Adds the metrics described in [feat][doc] PIP-264: Add broker connection metrics pulsar-site#921 to the collector runs.

Verifying this change

• Make sure that the change passes the CI checks.

This change added tests and can be verified as follows:

• Added test in org.apache.pulsar.broker.stats.OpenTelemetryBrokerOperabilityStatsTest

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

• Dependencies (add or upgrade a dependency)
• The public API
• The schema
• The default values of configurations
• The threading model
• The binary protocol
• The REST endpoints
• The admin CLI options
• The metrics: As described in [feat][doc] PIP-264: Add broker connection metrics pulsar-site#921
• Anything that affects deployment

Documentation

• doc
• doc-required [feat][doc] PIP-264: Add broker connection metrics pulsar-site#921
• doc-not-needed
• doc-complete

Matching PR in forked repository

PR in forked repository: dragosvictor#28