[Admin] Add @xinruiba as a maintainer

[Flyingliuhub]

Description

Updates MAINTAINERS.md and .github/CODEOWNERS.

Here are xinruiba's current merge contributions, total contributions, and issues:
Successfully merging numerous pull requests (PRs)
Providing valuable reviews for PRs
Addressing and resolving various issues

Check List

• All tests pass
  • yarn test:jest
  • yarn test:jest_integration
• New functionality includes testing.
• New functionality has been documented.
• Update CHANGELOG.md
• Commits are signed per the DCO using --signoff

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 67.31%. Comparing base (de978d4) to head (2900c03).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #6217   +/-   ##
=======================================
  Coverage   67.31%   67.31%           
=======================================
  Files        3348     3348           
  Lines       64966    64966           
  Branches    10465    10465           
=======================================
  Hits        43729    43729           
  Misses      18690    18690           
  Partials     2547     2547           

Flag	Coverage Δ
Linux_1	31.72% <ø> (ø)
Linux_2	55.55% <ø> (ø)
Linux_3	44.68% <ø> (ø)
Linux_4	35.02% <ø> (ø)
Windows_1	31.74% <ø> (ø)
Windows_2	55.52% <ø> (ø)
Windows_3	44.68% <ø> (ø)
Windows_4	35.02% <ø> (ø)

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[opensearch-trigger-bot]

The backport to 2.x failed:

The process '/usr/bin/git' failed with exit code 128

To backport manually, run these commands in your terminal:

# Navigate to the root of your repository
cd $(git rev-parse --show-toplevel)
# Fetch latest updates from GitHub
git fetch
# Create a new working tree
git worktree add ../.worktrees/OpenSearch-Dashboards/backport-2.x 2.x
# Navigate to the new working tree
pushd ../.worktrees/OpenSearch-Dashboards/backport-2.x
# Create a new branch
git switch --create backport/backport-6217-to-2.x
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick -x --mainline 1 f103b7ed6c09285a5ff080022c14398c23fe6482
# Push it to GitHub
git push --set-upstream origin backport/backport-6217-to-2.x
# Go back to the original working tree
popd
# Delete the working tree
git worktree remove ../.worktrees/OpenSearch-Dashboards/backport-2.x

Then, create a pull request where the base branch is 2.x and the compare/head branch is backport/backport-6217-to-2.x.

[Flyingliuhub]

@opensearch-project/admin could you add @xinruiba to a maintainer.