feat(css): Migrate CSS to utility classes in escalation_policies.scss

What does this MR do and why?

Migrate CSS rules to utility classes in app/assets/stylesheets/page_bundles/escalation_policies.scss

Resolves this issue

Screenshots or screen recordings

Before	After

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How to set up and validate locally

• Checkout to 367786-migrate-css-rules branch
• Run gdk
• Go to Monitor -> Escalation policies

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.

Related to #367786 (closed)