wayland: Ignore touch events in seat default focus handler

Touch events are implicitly grabbed to the surface they began in,
and are not affected by the focus handler. However these events
will appear to come from the core pointer device, which might lead
to the wrong device being updated.

Ignore events with a sequence, since the default focus handler
does not intend to do anything with them.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/3889>
(cherry picked from commit 08c903a359)

src/wayland/meta-wayland-seat.c

@@ -215,6 +215,9 @@ default_focus (MetaWaylandEventHandler *handler,
   MetaWaylandSeat *seat = user_data;
   ClutterInputCapabilities caps;
 
+  if (sequence)
+    return;
+
   caps = clutter_input_device_get_capabilities (device);
 
   if (caps &