[AUTO] Add release notes for 3.4.0

[opensearch-ci-bot]

Add release notes for 3.4.0

[coderabbitai]

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✨ Finishing touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment
• Commit unit tests in branch release-chores/release-notes-3.4.0

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
⚠️ Please upload report for BASE (3.4@743115e). Learn more about missing BASE report.

Additional details and impacted files

@@          Coverage Diff           @@
##             3.4    #4501   +/-   ##
======================================
  Coverage       ?   80.16%           
  Complexity     ?    10238           
======================================
  Files          ?      858           
  Lines          ?    44517           
  Branches       ?     5151           
======================================
  Hits           ?    35685           
  Misses         ?     6667           
  Partials       ?     2165           

Flag	Coverage Δ
ml-commons	80.16% <ø> (?)

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[Divyaasm]

@b4sjoo , can we have this merged and backported to main branch

[b4sjoo]

Close as it's added manually.