[Accessibility] Primary badge in dark mode doesn't have enough contrast

[afgomez]

When using the dark palette, the text color on an <EuiBadge color="primary" /> doesn't have enough contrast with the background, according to the contrast calculator in the Chrome devtools.

[cchaos]

Thanks @afgomez. I'm going to call this a duplicate of #1894 and we already of a WIP PR to fix these #2455

[afgomez]

ah! thanks :)