[improve][broker] Reuse topic OpenTelemetry attributes

[dragosvictor]

Fixes #22817

Motivation

Successive collections of OpenTelemetry metrics re-allocate all attribute sets related to a topic. Since topics are a high-cardinality object in Pulsar, this puts pressure on the GC. This PR proposes caching these attribute sets.

Modifications

• Adds classes TopicAttributes and PersistentTopicAttributes to store all attribute sets relevant for a topic.
• Add and lazily initialize these attribute fields in the NonPersistentTopic and PersistentTopic objects. If OpenTelemetry is not enabled, these objects never get created, saving memory.
• Modify OpenTelemetryTopicStats to use the cached objects instead of re-allocating them every run.
• Relocate some of the attributes into interface OpenTelemetryAttributes, for a cleaner design.

Verifying this change

• Make sure that the change passes the CI checks.

This change is already covered by existing tests, such as org.apache.pulsar.broker.stats.OpenTelemetryTopicStatsTest.

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
• The metrics
• Anything that affects deployment

Documentation

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

Matching PR in forked repository

PR in forked repository: dragosvictor#31

[lhotari]

LGTM, nice work @dragosvictor

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 94.25287% with 5 lines in your changes missing coverage. Please review.

Project coverage is 73.25%. Comparing base (bbc6224) to head (e30dae9).
Report is 734 commits behind head on master.

Files with missing lines	Patch %	Lines
...oker/service/nonpersistent/NonPersistentTopic.java	33.33%	4 Missing ⚠️
...sar/broker/service/persistent/PersistentTopic.java	83.33%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##             master   #22876      +/-   ##
============================================
- Coverage     73.57%   73.25%   -0.33%     
- Complexity    32624    32994     +370     
============================================
  Files          1877     1891      +14     
  Lines        139502   141935    +2433     
  Branches      15299    15565     +266     
============================================
+ Hits         102638   103970    +1332     
- Misses        28908    29939    +1031     
- Partials       7956     8026      +70     

Flag	Coverage Δ
inttests	27.25% <87.35%> (+2.67%)	⬆️
systests	24.66% <2.29%> (+0.34%)	⬆️
unittests	72.27% <94.25%> (-0.57%)	⬇️

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

Files with missing lines	Coverage Δ
...lsar/broker/service/PersistentTopicAttributes.java	100.00% <100.00%> (ø)
...n/java/org/apache/pulsar/broker/service/Topic.java	33.33% <ø> (-3.04%)	⬇️
.../apache/pulsar/broker/service/TopicAttributes.java	100.00% <100.00%> (ø)
...e/pulsar/broker/stats/OpenTelemetryTopicStats.java	99.06% <100.00%> (ø)
.../pulsar/opentelemetry/OpenTelemetryAttributes.java	100.00% <100.00%> (ø)
...sar/broker/service/persistent/PersistentTopic.java	79.21% <83.33%> (+0.75%)	⬆️
...oker/service/nonpersistent/NonPersistentTopic.java	70.52% <33.33%> (+1.06%)	⬆️

... and 382 files with indirect coverage changes

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