Remap few colors for EuiLoadingSpinner and EuiLoadingChart

[ek-so]

Summary

This PR:

• Changes grey shades used for the EuiLoadingChart in mono version in dark mode:
  
• Maps EuiLoadingSpinner to unilize Borealis tokens instead of old Amsterdam tokens.
  

QA

Remove or strikethrough items that do not apply to your PR.

General checklist

• Browser QA
  • Checked in both light and dark modes
  • Checked in mobile
  • Checked in Chrome, Safari, Edge, and Firefox
  • Checked for accessibility including keyboard-only and screenreader modes
• Docs site QA
  • Added documentation
  • Props have proper autodocs (using @default if default values are missing) and playground toggles
  • Checked Code Sandbox works for any docs examples
• Code quality checklist
  • Added or updated jest and cypress tests
  • Updated visual regression tests
• Release checklist
  • A changelog entry exists and is marked appropriately.
  • If applicable, added the breaking change issue label (and filled out the breaking change checklist)
• Designer checklist
  • If applicable, file an issue to update EUI's Figma library with any corresponding UI changes. (This is an internal repo, if you are external to Elastic, ask a maintainer to submit this request)

[kibanamachine]

Preview staging links for this PR:

• Docs site: https://eui.elastic.co/pr_8276/
• Storybook: https://eui.elastic.co/pr_8276/storybook
• New docs: https://eui.elastic.co/pr_8276/new-docs

[elasticmachine]

💚 Build Succeeded

• Buildkite Build
• Commit: 1b768e7

History

• 💚 Build #3326 succeeded d6ee13a
• 💔 Build #3324 failed cf3bc4f

cc @mgadewoll

[mgadewoll]

🚢 🐈‍⬛ Great work on the updates! Thanks a lot for contributing! 🎉