patch 8.2.4709: after :redraw the statusline highlight might be used

Problem:    After :redraw the statusline highlight might be used.
Solution:   Clear the screen attribute after redrawing the screen.
            (closes #10108)

src/ex_docmd.c

@@ -8290,6 +8290,9 @@ ex_redraw(exarg_T *eap)
     RedrawingDisabled = r;
     p_lz = p;
 
+    // After drawing the statusline screen_attr may still be set.
+    screen_stop_highlight();
+
     // Reset msg_didout, so that a message that's there is overwritten.
     msg_didout = FALSE;
     msg_col = 0;