React compatibility: Use new createRoot API

[coder-karen]

Issue

In React 18, importing createRoot from react-dom was deprecated, so ideally we'll fix up instances of this.

Related warnings:

Warning: You are importing createRoot from "react-dom" which is not supported. You should instead import it from "react-dom/client". visible on the Jetpack settings page.

Parent React 19 compatibility issue: #37951

[anomiex]

Looks like just one instance was added since this was previously fixed in #28710.

jetpack/projects/js-packages/components/components/boost-score-graph/tooltips-plugin.ts

Line 26 in d17273c

reactDom = ReactDOM.createRoot( reactRoot );

[coder-karen]

Thanks! Looks like there are two separate issues related to createRoot, so I'll address them both.
Edit - no - just the one, thanks for clarifying in the PR!