[Backport 2.x] Improve performance of encoding composite keys in multi-term aggregations

[opensearch-trigger-bot]

Backport 46f2bd0 from #9412.

[opensearch-trigger-bot]

Compatibility status:

Checks if related components are compatible with change 2b6fa05

Incompatible components

Incompatible components: [https://github.com/opensearch-project/index-management.git, https://github.com/opensearch-project/alerting.git, https://github.com/opensearch-project/performance-analyzer.git]

Skipped components

Compatible components

Compatible components: [https://github.com/opensearch-project/geospatial.git, https://github.com/opensearch-project/security.git, https://github.com/opensearch-project/notifications.git, https://github.com/opensearch-project/neural-search.git, https://github.com/opensearch-project/security-analytics.git, https://github.com/opensearch-project/sql.git, https://github.com/opensearch-project/job-scheduler.git, https://github.com/opensearch-project/k-nn.git, https://github.com/opensearch-project/observability.git, https://github.com/opensearch-project/anomaly-detection.git, https://github.com/opensearch-project/asynchronous-search.git, https://github.com/opensearch-project/cross-cluster-replication.git, https://github.com/opensearch-project/common-utils.git, https://github.com/opensearch-project/performance-analyzer-rca.git, https://github.com/opensearch-project/reporting.git, https://github.com/opensearch-project/ml-commons.git]

[github-actions]

Gradle Check (Jenkins) Run Completed with:

• RESULT: SUCCESS ✅
• URL: https://build.ci.opensearch.org/job/gradle-check/23030/
• CommitID: c7eddca

[codecov]

Codecov Report

Merging #9434 (c7eddca) into 2.x (2b6fa05) will decrease coverage by 0.01%.
The diff coverage is 94.64%.

@@             Coverage Diff              @@
##                2.x    #9434      +/-   ##
============================================
- Coverage     70.90%   70.89%   -0.01%     
- Complexity    57628    57651      +23     
============================================
  Files          4762     4762              
  Lines        272064   272081      +17     
  Branches      40111    40110       -1     
============================================
+ Hits         192895   192898       +3     
- Misses        62636    62655      +19     
+ Partials      16533    16528       -5     

Files Changed	Coverage Δ
...ggregations/bucket/terms/MultiTermsAggregator.java	82.07% <93.75%> (+2.88%)	⬆️
...opensearch/core/common/io/stream/StreamOutput.java	94.56% <100.00%> (+0.01%)	⬆️

... and 446 files with indirect coverage changes