Scrollviewer scrolls when scrolling inside datagrid

[SamBent]

[Port of a servicing fix in .NET 4.7-4.8]

Problem description:
DataGrid contains a ScrollViewer. When DataGrid is itself contained in an outer ScrollViewer, calling ScrollIntoView can scroll both ScrollViewers even when the outer scroll is unnecessary.

[SamBent]

Fix ported to 3.1.19, 5.0.10, 6.0.