Fixes from spec 2704

[l-trotta]

Update to the generated code from the latest specification and code-generator. This includes https://github.com/elastic/elasticsearch-specification/pull/2794, which fixes https://github.com/elastic/elasticsearch-java/issues/826, fixes https://github.com/elastic/elasticsearch-java/issues/831, fixes https://github.com/elastic/elasticsearch-java/issues/834, fixes https://github.com/elastic/elasticsearch-java/issues/835, fixes https://github.com/elastic/elasticsearch-java/issues/842.

[github-actions[bot]]

The backport to 8.15 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-8.15 8.15
# Navigate to the new working tree
cd .worktrees/backport-8.15
# Create a new branch
git switch --create backport-844-to-8.15
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick --mainline 1 c605efa5e9d2ff11768adbc6edec7e22cca73f63
# Push it to GitHub
git push --set-upstream origin backport-844-to-8.15
# Go back to the original working tree
cd ../..
# Delete the working tree
git worktree remove .worktrees/backport-8.15

Then, create a pull request where the base branch is 8.15 and the compare/head branch is backport-844-to-8.15.