patch 9.1.1451: tabpanel rendering artifacts when scrolling

Problem:  tabpanel rendering artifacts when scrolling
Solution: update scrolling logic (Hirohito Higashi)

fixes: #17495
closes: #17496

Signed-off-by: Hirohito Higashi <h.east.727@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/window.c b/src/window.c
index bb11638..f3b23e8 100644
--- a/src/window.c
+++ b/src/window.c
@@ -6226,14 +6226,7 @@
 
     if (!skip_win_fix_scroll)
 	win_fix_scroll(TRUE);
-#ifdef FEAT_GUI
-    if (gui.in_use && !gui.starting)
-    {
-	if (scroll_region)
-	    scroll_region_reset();
-	scroll_start();	// may scroll the screen to the right position
-    }
-#endif
+
     redraw_tabline = TRUE;
 #if defined(FEAT_TABPANEL)
     redraw_tabpanel = TRUE;