[feat][broker] Expose pulsar out bytes and message metrics per topic

[pgier]

Add prometheus metrics which expose the per topic messages out and bytes out total on a per topic basis. Currently, only the subscription level stats are enabled.

Motivation

There are currently two metrics pulsar_out_bytes_total and pulsar_out_messages_total. The metrics represent the pulsar stats on a per subscription basis. It would be convenient to be able to see the summary of these values per topic similar to the stats exposed by pulsar-admin.

Modifications

Added the two metrics and updated the test to verify that the output is correct.

Verifying this change

• [X] Make sure that the change passes the CI checks.

This change is already covered by existing tests, such as (please describe tests). I made an enhancement to the existing Promtheus metrics test.

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

If the box was checked, please highlight the changes

• [ ] 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
• [ ] Anything that affects deployment

Documentation

• [ ] doc
• [ ] doc-required
• [X] doc-not-needed
• [ ] doc-complete

Matching PR in forked repository

PR in forked repository: https://github.com/pgier/pulsar/pull/1

[codecov-commenter]

Codecov Report

Merging #18440 (94dc7df) into master (fdf86d3) will decrease coverage by 1.64%. The diff coverage is 0.00%.

@@             Coverage Diff              @@
##             master   #18440      +/-   ##
============================================
- Coverage     45.67%   44.03%   -1.64%     
- Complexity    10075    18476    +8401     
============================================
  Files           693     1791    +1098     
  Lines         67940   155298   +87358     
  Branches       7273    19054   +11781     
============================================
+ Hits          31030    68392   +37362     
- Misses        33333    79241   +45908     
- Partials       3577     7665    +4088     

Flag	Coverage Δ
inttests	23.40% <0.00%> (?)
systests	24.13% <0.00%> (?)
unittests	42.86% <0.00%> (-2.82%)	:arrow_down:

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
...che/pulsar/broker/stats/prometheus/TopicStats.java	10.59% <0.00%> (+10.59%)	:arrow_up:

... and 1461 files with indirect coverage changes

[github-actions[bot]]

The pr had no activity for 30 days, mark with Stale label.

[RobertIndie]

/pulsarbot run-failure-checks

[cbornet]

@pgier there's a test failure: https://github.com/apache/pulsar/actions/runs/4664751844/jobs/8257572250?pr=18440#step:11:1521 Can you check ?

[github-actions[bot]]

The pr had no activity for 30 days, mark with Stale label.