Throttling info in DeleteByQueryResponse is optional

[swallez]

As titled. Reported in elastic/elasticsearch-java#413

[github-actions]

Following you can find the validation results for the API you have changed.

API	Status	Request	Response
delete_by_query	🟢	5/5	4/4

You can validate this API yourself by using the make validate target.

[Anaethelion]

LGTM

[github-actions]

The backport to 7.17 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-7.17 7.17
# Navigate to the new working tree
cd .worktrees/backport-7.17
# Create a new branch
git switch --create backport-2147-to-7.17
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick --mainline 1 902222a6495852a7443d24b8a0bf1223b96414e6
# Push it to GitHub
git push --set-upstream origin backport-2147-to-7.17
# Go back to the original working tree
cd ../..
# Delete the working tree
git worktree remove .worktrees/backport-7.17

Then, create a pull request where the base branch is 7.17 and the compare/head branch is backport-2147-to-7.17.