Trigger scroll on scrolled selection (microsoft#5798)

## Summary of the Pull Request
We accidentally missed switching one `TriggerRedrawAll` to `TriggerScroll`. This does that.

## References
microsoft#5185 - applies logic from this PR

## PR Checklist
* [X] Closes microsoft#5756

## Validation Steps Performed
Followed bug repro steps.

src/cascadia/TerminalCore/terminalrenderdata.cpp

@@ -167,7 +167,7 @@ void Terminal::SelectNewRegion(const COORD coordStart, const COORD coordEnd)
 
     if (notifyScrollChange)
     {
-        _buffer->GetRenderTarget().TriggerRedrawAll();
+        _buffer->GetRenderTarget().TriggerScroll();
         _NotifyScrollEvent();
     }