[Backport 2.x] Makes sure KNNVectorValues aren't recreated unnecessarily when

[opensearch-trigger-bot[bot]]

Backport e33afa5de5f8658ad7fbe71125707436e81cc5b8 from #2133

[opensearch-trigger-bot[bot]]

The backport to 2.17 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-2.17 2.17
# Navigate to the new working tree
cd .worktrees/backport-2.17
# Create a new branch
git switch --create backport/backport-2137-to-2.17
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick -x --mainline 1 33c05ead48e636585c7b743c7cb26c129c861876
# Push it to GitHub
git push --set-upstream origin backport/backport-2137-to-2.17
# Go back to the original working tree
cd ../..
# Delete the working tree
git worktree remove .worktrees/backport-2.17

Then, create a pull request where the base branch is 2.17 and the compare/head branch is backport/backport-2137-to-2.17.