Tweak Clocks world clock test removal loop to be more robust

We need to move the mouse out of the way so we don't need two
needles for "X not highlighted" and "X highlighted", and give
the check_screen a few seconds to update for the cursor move.

Signed-off-by: Adam Williamson <awilliam@redhat.com>

tests/applications/clocks/world.pm

@@ -38,8 +38,9 @@ sub run {
 
     # Click onto the Delete button to remove the listed cities.
     # While there are cities to be removed, remove them.
-    while (check_screen("gnome_button_cross_remove")) {
+    while (check_screen("gnome_button_cross_remove", 3)) {
         click_lastmatch();
+        mouse_hide;
     }
     # If the cities are still visible, then die.
     if (check_screen("clocks_city_added_bratislava")) {