Fix clearing an OptionList

See #2557, credit to Will:

  https://github.com/Textualize/textual/issues/2557#issuecomment-1546883815

src/textual/widgets/_option_list.py

@@ -631,7 +631,7 @@ class OptionList(ScrollView, can_focus=True):
         self.highlighted = None
         self._mouse_hovering_over = None
         self.virtual_size = Size(self.scrollable_content_region.width, 0)
-        self.refresh()
+        self._request_content_tracking_refresh()
         return self
 
     def _set_option_disabled(self, index: int, disabled: bool) -> Self: