Standardize primary hue across design system

[aaazzam]

Prefect uses hsl(228+-, 6+-, lightness) to parameterize a family of blues to create depth throughout its UI.

This PR collapses the small variations in hue and saturation to create a better-practice family of background depths.

The thirteen or so primary color variations are collapsed to the single one in red:

This has little-to-no visual distinction in the UI, but sets us up for a better devex against this smaller surface area of colors.

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