[data grid] disable processor cleanups in development / testing

[lauri865]

• I have followed (at least) the PR section of the contributing guide.

Trying to fix a hairy issue discovered here:
#16395 (comment)

The problem is that useFirstRender doesn't work properly in StrictMode. It is only called once, but everything else is called twice, meaning that processors are improperly cleaned up. Trying to see if we can just disable cleanups in development to preserve the functionality of useFirstRender with StrictMode.

If useFirstRender doesn't work properly with StrictMode, and we cleanup processors incorrectly, we have a few problems:

• processors might not silently work, because they are only registered in useEffect, so ordering of hooks is extremely important in useDatagridComponent hook
• it might lead to writing unoptimised code that waits a few cycles until it works, that's only to make tests pass / StrictMode happy

[mui-bot]

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