Add a comment regarding performance of v-html

What does this MR do and why?

With !57842 (merged) we reverted v-safe-html to v-html for performance reasons. This adds a comment so that we do not cause the same problems again.

Screenshots or screen recordings

N/A

How to set up and validate locally

N/A

MR acceptance checklist

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

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