main: Stop owning the org.gnome.Panel name

This is a relict from the pre-3.0 days, when it was common to
replace a running GNOME 2 session with gnome-shell. There has
been no good reason to claim the name for many years, time to
drop it.

If someone really wants to run gnome-panel alongside the shell,
they probably know what they are doing. Or cannot be helped anyway.

Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/1521>

src/main.c

@@ -157,9 +157,7 @@ shell_dbus_init (gboolean replace)
 
   shell_dbus_acquire_names (bus,
                             request_name_flags,
-  /* Also grab org.gnome.Panel to replace any existing panel process */
-                            "org.gnome.Panel", TRUE,
-  /* ...and the org.gnome.Magnifier service. */
+  /* Also grab the org.gnome.Magnifier service. */
                             MAGNIFIER_DBUS_SERVICE, FALSE,
                             NULL);
   g_object_unref (bus);