[docs] Avoid crash in demos using row grouping and custom formatted cells

[m4theushw]

1. Open https://master--material-ui-x.netlify.app/components/data-grid/group-pivot/#full-example
2. Scroll all the way to the right
3. 💥

I noticed while reviewing #4030

A better solution would be to not render the cells in auto-generated rows, but we have the problem where we need to call getCellParams to pass to cellClassName which calls the value formatter.

[mui-bot]

These are the results for the performance tests:

Test case	Unit	Min	Max	Median	Mean	σ
Filter 100k rows	ms	225	391.6	369.8	317.6	75.42
Sort 100k rows	ms	384.8	895.3	708.6	648.2	178.706
Select 100k rows	ms	155.3	304.7	182.5	202.78	54.368
Deselect 100k rows	ms	90.2	275.4	139.4	155.06	62.852

Generated by 🚫 dangerJS against c1a6999

[flaviendelangle]

A better solution would be to not render the cells in auto-generated rows

In some scenarios, rendering those cells can be useful.
But I agree that we could improve how it works.

I am also fixing it in /~https://github.com/mui/mui-x/pull/4064/files#diff-8dad26ca77285751ab928cda82ebfe0d7d6e97863d735aadf17a633a8bd72f76R248.