[core] Remove dead code

[oliviertassinari]

I have found this by looking into #4280 in more detail. This code path is never reached, it seemed to have been here for when we implemented the virtualization without using a native scroll container, so we had to reset the scrollLeft and scrollRight. This is no longer the case.

[mui-bot]

These are the results for the performance tests:

Test case	Unit	Min	Max	Median	Mean	σ
Filter 100k rows	ms	231.2	432.7	332.1	330.42	85.358
Sort 100k rows	ms	434.6	906.7	698.5	701.86	179.822
Select 100k rows	ms	114.9	294.9	143.1	175.7	63.739
Deselect 100k rows	ms	93.4	270.9	209.7	187.2	57.28

Generated by 🚫 dangerJS against c559916

[m4theushw]

Yeah, it's legacy. We can also remove the following ref now:

mui-x/packages/grid/x-data-grid/src/components/base/GridBody.tsx

Line 64 in ed594d7

apiRef.current.renderingZoneRef = renderingZoneRef; // TODO remove, nobody should have access to internal parts of the virtualization

[oliviertassinari]

We can also remove the following ref now:

Likely! I will resist the urge to spend more time on the code side by merging 😁