Delete CHANGELOG.md as it has not been used and cause issues in autogen release notes

[peterzhuamazon]

Description

Delete CHANGELOG.md as it has not been used and cause issues in autogen release notes

Issues Resolved

In 3.3 we try to autogen release notes, but since this file exist it take priority.
If you havent update this file since 3.0, we would suggest remove it and let AI autogen take over release notes.

Thanks.

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[opensearch-trigger-bot]

The backport to 2.x failed:

The process '/usr/bin/git' failed with exit code 1

To backport manually, run these commands in your terminal:

# Fetch latest updates from GitHub
git fetch
# Create a new working tree
git worktree add .worktrees/backport-2.x 2.x
# Navigate to the new working tree
cd .worktrees/backport-2.x
# Create a new branch
git switch --create backport/backport-1102-to-2.x
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick -x --mainline 1 033df9e3a9851380a95083c9566c118a9bfbaa25
# Push it to GitHub
git push --set-upstream origin backport/backport-1102-to-2.x
# Go back to the original working tree
cd ../..
# Delete the working tree
git worktree remove .worktrees/backport-2.x

Then, create a pull request where the base branch is 2.x and the compare/head branch is backport/backport-1102-to-2.x.