[DataGridPro] Do not expand row children when pressing Shift + Space

[flaviendelangle]

Extracted from #3277

Shift + Space is selecting / unselecting the row, the children selection should only be applied when pressing Space without Shift

I also added two small core improvements

• Do the groupingColDef computation in a useCallback instead of a useMemo to avoid running the prop.groupingColDef callback version on the tree data grouping column when the tree data is not enabled.
• Use the rowNode from the params in the cellKeyDown event instead of using the apiRef (helps us remove an useless check)