cinnamon-window-tracker: Use a different method for matching

existing apps and new windows by pid.

Muffin now emits workspace::window-added and ::removed for
each workspace when a window is initially on-all-workspaces
(stuck). This was resulting in things like the shutdown dialog
window being associated with (2 * n_workspaces) CinnamonApps,
then throwing lots of warnings when it closed.

based on:
https://gitlab.gnome.org/GNOME/gnome-shell/-/commit/186f9b2e2c169f6625b363689e707d7f9befbc2f

Author: mtwebster

src/cinnamon-window-tracker.c

@@ -409,7 +409,7 @@ get_app_from_window_group (CinnamonWindowTracker  *tracker,
  * @window: a #MetaWindow
  *
  * Check if the pid associated with @window corresponds to an
- * application we launched.
+ * application.
  *
  * Return value: (transfer full): A newly-referenced #CinnamonApp, or %NULL
  */
@@ -425,10 +425,10 @@ get_app_from_window_pid (CinnamonWindowTracker  *tracker,
 
   pid = meta_window_get_pid (window);
 
-  if (pid == -1)
+  if (pid < 1)
     return NULL;
 
-  result = g_hash_table_lookup (tracker->launched_pid_to_app, GINT_TO_POINTER (pid));
+  result = cinnamon_window_tracker_get_app_from_pid (tracker, pid);
   if (result != NULL)
     g_object_ref (result);