Remove unused alias in webpack config

What does this MR do and why?

This change removes two unused aliases from our webpack config.

Aliases empty_states and icons are not used in any of our imports so they can be safely removed.

Screenshots or screen recordings

NA

How to set up and validate locally

As long as our compile-production-assets passes we should be safe. I checked that there were no imports that matched these patterns.

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.