Make AutoScrollToFirstChange() work reliably in Side-By-Side Diff

Both of the SingleSideTextDiffPresenter instances need to be scrolled/synced for this to work reliably.

(To see where it failed, open a Side-By-Side Diff where the first change-block would be out-of-view, then toggle `Show All Lines` - when enabling the latter, the first change-block would NOT be correctly scrolled-to.)

Author: goran-w

src/Views/TextDiffView.axaml.cs

@@ -805,9 +805,6 @@ private void AutoScrollToFirstChange()
             if (DataContext is not ViewModels.TextDiffContext ctx)
                 return;
 
-            if (ctx.IsSideBySide() && !IsOld)
-                return;
-
             var curBlock = ctx.BlockNavigation.GetCurrentBlock();
             if (curBlock == null)
                 return;