Branch protection improvements

FYI I just created a ruleset for this repo: https://github.com/nodejs/node-core-utils/settings/rules/4654889

It targets the default branch and enables:

• Restrict deletions
• Require linear history
• Require a pull request with at least one approval
• Block force pushes

Only the pull request requirements are new compared to the old branch protection rule (https://github.com/nodejs/node-core-utils/settings/branch_protection_rules/17880641)
I think we can delete that rule. The only thing that remains in it is the restriction of who can push and that only restricts the nodejs-github-bot account. I don't think there's a convenient way to port that to rulesets. We could use the bypass list but then every pull request would always be red and require collaborators to click the bypass checkbox.

リンク先のGitHubリポジトリ設定ページにあるルールセットを確認し、既存のブランチ保護ルールと比較してください。古いルールのnodejs-github-botに対するpush制限を、pull requestに支障をきたすことなく置き換えるか削除できるか確認してください。完了条件は、リポジトリに意図した単一のブランチ保護設定が存在することです。