Register pty cleanup function in exec_pty(), not exec_cmnd_pty().

We want it to execute in the main sudo process, not the monitor.

src/exec_monitor.c

@@ -1,7 +1,7 @@
 /*
  * SPDX-License-Identifier: ISC
  *
- * Copyright (c) 2009-2022 Todd C. Miller <Todd.Miller@sudo.ws>
+ * Copyright (c) 2009-2023 Todd C. Miller <Todd.Miller@sudo.ws>
  *
  * Permission to use, copy, modify, and distribute this software for any
  * purpose with or without fee is hereby granted, provided that the above
@@ -354,9 +354,6 @@ exec_cmnd_pty(struct command_details *details, sigset_t *mask,
     volatile pid_t self = getpid();
     debug_decl(exec_cmnd_pty, SUDO_DEBUG_EXEC);
 
-    /* Register cleanup function */
-    sudo_fatal_callback_register(pty_cleanup);
-
     /* Set command process group here too to avoid a race. */
     setpgid(0, self);