fix: color errors due to fillColor changes in v54.0.0

[nickofthyme]

Summary

This PR fixes errors in partition chart coloring due to fillColor api changes in v54.0.0 (from elastic/elastic-charts#1956).

We missed this change in updating chart in #6641 with 6 breaking changes. Also we have become accustom to typescript flagging errors like this but all errors in this case were in js files 😭.

This changed the API where the first param of the fillColor function is the Key of the layer and not the entire Node. The second param is now the sortIndex used in many places in the EUI docs.

- export type NodeColorAccessor = (d: ShapeTreeNode, index: number, array: HierarchyOfArrays) => string;
+ export type NodeColorAccessor = (key: Key, sortIndex: number, node: ArrayNode, tree: HierarchyOfArrays) => string

[kibanamachine]

Preview staging links for this PR:

• Docs site: https://eui.elastic.co/pr_7271/
• Storybook: https://eui.elastic.co/pr_7271/storybook

[elasticmachine]

💚 Build Succeeded

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• Commit: a3747d4

[cee-chen]

❤️ Thanks for grabbing this Nick! I can confirm the console error is gone in staging.

Also we have become accustom to typescript flagging errors like this but all errors in this case were in js files 😭.

We can totally change the charts docs pages to TS if you're down for that - totally up to you, of course!