Update deprecated openAI mode in integration test and fix flaky tests

[Hailong-am]

Description

This PR includes changes for below items

1. pick from fix flaky test due to localization #1734
2. part of Fix sort on get trace API and flaky test of conversation #1733
3. replace deprecated openAI mode in integration test
4. update default admin password for integration test with docker run
5. fix getConversations when index not exists missing return

Issues Resolved

#1848 and #1849

Check List

• New functionality includes testing.
  • All tests pass
• New functionality has been documented.
  • New functionality has javadoc added
• Commits are signed per the DCO using --signoff

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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-1846-to-2.x
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick -x --mainline 1 6584529ebc4554d25d8ba664913b2fab7e644c0e
# Push it to GitHub
git push --set-upstream origin backport/backport-1846-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-1846-to-2.x.