[charts] Pie chart loading text not localizable

### Steps to reproduce

https://github.com/mui/mui-x/blob/fd688626ec58f714590cfbb6f52261e1c4b135f6/docs/data/charts/styling/CustomOverlay.tsx#L47-L49

### Current behavior

Loading data.. is not localisable. hard coded in

### Expected behavior

should be localisable

### Your environment

<details>
  <summary><code>npx @mui/envinfo</code></summary>

```
 System:
    OS: Linux 6.11 Ubuntu 24.10 24.10 (Oracular Oriole)
  Binaries:
    Node: 20.16.0 - /usr/bin/node
    npm: 9.2.0 - /usr/bin/npm
    pnpm: 9.15.5 - /usr/local/bin/pnpm
  Browsers:
    Chrome: Not Found

~$ 

```
</details>



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[charts] Pie chart loading text not localizable #16963

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	<LoadingText x={left + width / 2} y={top + height / 2}>
	Loading data ...
	</LoadingText>

Uh oh!

[charts] Pie chart loading text not localizable #16963

Description

Steps to reproduce

Current behavior

Expected behavior

Your environment

Metadata

Metadata

Assignees

Labels

Projects

Milestone

Relationships

Development

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