fix(checkbox): Replace unique-id with custom color hash function to generate keyframes

[abhiomkar]

Project import generated by Copybara.

[googlebot]

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[googlebot]

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[mdc-web-bot]

All 698 screenshot tests passed for commit e7c1797 vs. master! 💯🎉

[mdc-web-bot]

All 698 screenshot tests passed for commit a937587 vs. master! 💯🎉