[6.x] EUI 5.8.1 comes with a brand color refresh. Also removes lots o…

…f KUI (#27009) (#27429)

* EUI 5.8.1 comes with a brand color refresh. Also removes lots of KUI (#27009)

EUI 5.7.0 had a color refresh which switched around our palette to better match branding guidelines. Hex colors are still hard coded in large parts of Kibana so most of the changes not in kbn/ui-framework are simple shifts to match that styling.

* snapshots

package.json

@@ -109,7 +109,7 @@
   },
   "dependencies": {
     "@elastic/datemath": "5.0.2",
-    "@elastic/eui": "5.6.2",
+    "@elastic/eui": "5.8.1",
     "@elastic/filesaver": "1.1.2",
     "@elastic/good": "8.1.1-kibana2",
     "@elastic/numeral": "2.3.2",