[Upgrade] ICU4j from 68.2 to 70.1

[nknize]

Upgrades ICU4j to 70.1 to be consistent with Lucene 9.1 dependency.

[opensearch-ci-bot]

✅   Gradle Check success 991bc8e
Log 3512

Reports 3512

[opensearch-trigger-bot]

The backport to 1.3 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-1.3 1.3
# Navigate to the new working tree
cd .worktrees/backport-1.3
# Create a new branch
git switch --create backport/backport-2504-to-1.3
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick -x --mainline 1 e0ebf409648e69f9b4bf9c7c83bdea783c066d67
# Push it to GitHub
git push --set-upstream origin backport/backport-2504-to-1.3
# Go back to the original working tree
cd ../..
# Delete the working tree
git worktree remove .worktrees/backport-1.3

Then, create a pull request where the base branch is 1.3 and the compare/head branch is backport/backport-2504-to-1.3.