Use smaller and compressed varients of buttons and form components

[AMoo-Miki]

Replace instances of EuiButton that don't have an explicit sizing attribute to EuiSmallButton*.
Replace instances of Eui<form elements> that don't have density attributes to EuiCompressed<form elements>.

Check List

• New functionality includes testing.
  • All tests pass, including unit test, integration test.
• New functionality has user manual doc added.
• Commits are signed per the DCO using --signoff.

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.
For more information on following Developer Certificate of Origin and signing off your commits, please check here.

[ruanyl]

Thanks @AMoo-Miki, any background of these changes?(guess it's about look & feel) Are these changes for 2.17?

[AMoo-Miki]

Yes. They are all look and feel related. Also, please merge this as soon as you can. Not only is it for 2.17 but also, I won't be able to support the PRs much longer.

[SuZhou-Joe]

From the code changes, mostly are look & feel change but could you please post with a screenshot before and after so that we can easily tell if it is good enough for us to merge.

[opensearch-trigger-bot]

The backport to 2.x failed:

The process '/usr/bin/git' failed with exit code 128

To backport manually, run these commands in your terminal:

# Navigate to the root of your repository
cd $(git rev-parse --show-toplevel)
# Fetch latest updates from GitHub
git fetch
# Create a new working tree
git worktree add ../.worktrees/dashboards-assistant/backport-2.x 2.x
# Navigate to the new working tree
pushd ../.worktrees/dashboards-assistant/backport-2.x
# Create a new branch
git switch --create backport/backport-250-to-2.x
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick -x --mainline 1 9f8ed66c50c747aaeb6e48149ad29c8b1ccee027
# Push it to GitHub
git push --set-upstream origin backport/backport-250-to-2.x
# Go back to the original working tree
popd
# Delete the working tree
git worktree remove ../.worktrees/dashboards-assistant/backport-2.x

Then, create a pull request where the base branch is 2.x and the compare/head branch is backport/backport-250-to-2.x.