fix: no gunicorn control socket for the panel

gunicorn 26 opens a control socket in the service user's home, which
www-data cannot create, and logs an error at every start. The panel
does not use it.

gunicorn.conf.py

@@ -89,6 +89,8 @@ workers = get_workers()
 worker_connections = 1000
 timeout = 600
 keepalive = 2
+# gunicorn 26's control socket is unused, and the service user cannot create it
+control_socket_disable = True
 
 #
 # Debugging