[Sync 1.x with 1.3] Cookie splitter, release notes and version increment

[DarshitChanpura]

Synchronizes 1.x branch with 1.3

• Adds missing release notes (cherry-picked commit 307c7a0)
• [AUTO] Increment version to 1.3.15.0 #1698(cherry-picked commit fce71db)
• [Backport 1.3] Split up a value into multiple cookie payload #1831(cherry-picked commit 5f3efab)

Without cherry-picking it tried to add 10 additional commits which were already picked up in the last sync.

Check List

- [ ] New functionality includes testing
- [ ] New functionality has been documented

• Commits are signed per the DCO using --signoff

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 72.48%. Comparing base (0319257) to head (5f3efab).

Additional details and impacted files

@@           Coverage Diff           @@
##              1.x    #1752   +/-   ##
=======================================
  Coverage   72.48%   72.48%           
=======================================
  Files          88       88           
  Lines        1926     1926           
  Branches      251      251           
=======================================
  Hits         1396     1396           
  Misses        474      474           
  Partials       56       56           

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[DarshitChanpura]

CI will be fixed once artifact[1] to be published.

[1] - https://ci.opensearch.org/ci/dbc/distribution-build-opensearch/1.4.0/latest/linux/x64/tar/builds/opensearch/plugins/opensearch-security-1.4.0.0.zip