[EuiBadge] Update the docs to exemplify the HTTP status color codes used in Observability

[formgeist]

Summary

Related to #4508

I would like to update the component docs to exemplify the use of the euiPaletteForStatus in the badges for HTTP status code as it will be used in Observability. Currently, the component is only using the default color palette or custom colors. It would be nice to extend it to use the euiPaletteForStatus as well in this case.

[daveyholler]

@formgeist Heya buddy, is this issue still relevant?

[formgeist]

@daveyholler No, probably not - it was meant to help with coloring the status badges based on the status palette that could be generated from the palette helper. I just don't know if others outside APM and perhaps other apps in Observability are using badges for these use-cases.