If parameter queue_directory is defined and postfix is started via systemctl with `systemctl restart postfix` causes timeout issue.

Issue

• Postfix failed to start after changing queue_directory.

  #queue_directory = /var/spool/postfix
  queue_directory = /mailqueue
  

• Postfix unit fails with 'timeout'

  [root@localhost postfix]# systemctl start postfix
  Job for postfix.service failed because a timeout was exceeded.
  See "systemctl status postfix.service" and "journalctl -xe" for details.
  
  [root@localhost postfix]# systemctl status postfix.service
  ● postfix.service - Postfix Mail Transport Agent
     Loaded: loaded (/usr/lib/systemd/system/postfix.service; enabled; vendor preset: disabled)
     Active: failed (Result: timeout) since Fri 2023-08-18 05:40:23 BST; 1min 9s ago
    Process: 62423 ExecStart=/usr/sbin/postfix start (code=exited, status=0/SUCCESS)
    Process: 62421 ExecStartPre=/usr/libexec/postfix/chroot-update (code=exited, status=0/SUCCESS)
    Process: 62418 ExecStartPre=/usr/libexec/postfix/aliasesdb (code=exited, status=0/SUCCESS)
    Process: 62416 ExecStartPre=/usr/sbin/restorecon -R /var/spool/postfix/pid/master.pid (code=exited, status=0/SUCCESS)
  
  Aug 18 05:40:23 localhost systemd[1]: postfix.service: start operation timed out. Terminating.
  Aug 18 05:40:23 localhost systemd[1]: postfix.service: Failed with result 'timeout'.
  Aug 18 05:40:23 localhost systemd[1]: Failed to start Postfix Mail Transport Agent.