[DataGrid] Revert apiRef to be MutableRefObject for React versions < 19

[arminmeh]

Closes #16135

Because I would like to cherry pick this to v7 I have left these two items for a follow-up PR that will be for v8 only

• Changing types to include the possibility of apiRef being null - [data grid] Improve typing for useGridApiRef #16000
• Announce the breaking behavior in the migration guide

Results of these changes:
React 18

React 19

CC: @flaviendelangle @alexfauquette @LukasTy
We can extend this also to other packages

[mui-bot]

Deploy preview: https://deploy-preview-16279--material-ui-x.netlify.app/

Generated by 🚫 dangerJS against d914b33

[LukasTy]

Great work. 👍
Sorry for not testing thoroughly enough and thus not flagging this problem when working on the migration PR. 🙈

[arminmeh]

Great work. 👍 Sorry for not testing thoroughly enough and thus not flagging this problem when working on the migration PR. 🙈

Well, you were not alone in that 😅

[arminmeh]

@cherniavskii just to confirm and give a context for other as well.
We want to have the following outcome

for type T	v7	v8
R18	MutableRefObject<T>	MutableRefObject<T | null | undefined>
R19	RefObject<T>	RefObject<T | null>

Or R19 for v7 should also have null?

Update:

Types matrix

for type T	v7	v8
R18	MutableRefObject<T>	MutableRefObject<T | null>
R19	RefObject<T>	RefObject<T | null>

[cherniavskii]

@arminmeh For v8, either null or undefined are fine. Having both doesn't serve any additional purpose.

[cherniavskii]

👍🏻

[github-actions]

Cherry-pick PRs will be created targeting branches: v7.x