Fixes from spec pr 2959

[l-trotta]

Update to the generated code from the latest specification and code-generator. This includes elastic/elasticsearch-specification#2959, which fixes #877, fixes #880, fixes #881, fixes #883.

[github-actions]

The backport to 8.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-8.x 8.x
# Navigate to the new working tree
cd .worktrees/backport-8.x
# Create a new branch
git switch --create backport-887-to-8.x
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick --mainline 1 5d466ade855d62900150f52791abf3ef28bec6bf
# Push it to GitHub
git push --set-upstream origin backport-887-to-8.x
# Go back to the original working tree
cd ../..
# Delete the working tree
git worktree remove .worktrees/backport-8.x

Then, create a pull request where the base branch is 8.x and the compare/head branch is backport-887-to-8.x.