Revert "Merge branch 'emoji-picker-button-migration' into 'master'"

What does this MR do and why?

The merged migration of emoji picker buttons to GlButton (!134111 (merged)) caused a regression for custom emojis:

The change in HTML structure caused CSS for li.note img to be applied to custom emojis within the picker.

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How to set up and validate locally

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MR acceptance checklist

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