Fix include/exclude type in Frequent Items agg

[pquentin]

When working on #2279, I noticed that the Frequent Items set aggregation appears to reuse the standard include/exclude support, so I fixed it too.

I opened a different pull request because this aggregation is much more recent: it went GA for Elasticsearch 8.7. I would also appreciate guidance regarding the backports labels.

[github-actions]

The backport to 8.8 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-8.8 8.8
# Navigate to the new working tree
cd .worktrees/backport-8.8
# Create a new branch
git switch --create backport-2280-to-8.8
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick --mainline 1 fa57bcdbb1823eb2b62ee983f64f131f4b2fc02e
# Push it to GitHub
git push --set-upstream origin backport-2280-to-8.8
# Go back to the original working tree
cd ../..
# Delete the working tree
git worktree remove .worktrees/backport-8.8

Then, create a pull request where the base branch is 8.8 and the compare/head branch is backport-2280-to-8.8.

[github-actions]

The backport to 8.7 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-8.7 8.7
# Navigate to the new working tree
cd .worktrees/backport-8.7
# Create a new branch
git switch --create backport-2280-to-8.7
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick --mainline 1 fa57bcdbb1823eb2b62ee983f64f131f4b2fc02e
# Push it to GitHub
git push --set-upstream origin backport-2280-to-8.7
# Go back to the original working tree
cd ../..
# Delete the working tree
git worktree remove .worktrees/backport-8.7

Then, create a pull request where the base branch is 8.7 and the compare/head branch is backport-2280-to-8.7.

[github-actions]

The backport to 8.9 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-8.9 8.9
# Navigate to the new working tree
cd .worktrees/backport-8.9
# Create a new branch
git switch --create backport-2280-to-8.9
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick --mainline 1 fa57bcdbb1823eb2b62ee983f64f131f4b2fc02e
# Push it to GitHub
git push --set-upstream origin backport-2280-to-8.9
# Go back to the original working tree
cd ../..
# Delete the working tree
git worktree remove .worktrees/backport-8.9

Then, create a pull request where the base branch is 8.9 and the compare/head branch is backport-2280-to-8.9.

[pquentin]

Backports:

• 8.7: not backporting as this was only specified in 8.8
• [Backport 8.8] Fix include/exclude type in Frequent Items agg (#2280) #2288
• [Backport 8.9] Fix include/exclude type in Frequent Items agg (#2280) #2289
• [Backport 8.10] Fix include/exclude type in Frequent Items agg #2286