Kea DHCP Server not running

https://redmine.pfsense.org/issues/14977

If for some reason the Kea control socket lock file is present while Kea is stopped, then Kea can never start until that file is removed.

Attempting to start Kea while /tmp/kea4-ctrl-socket.lock exists, even if Kea is not currently running, results in a fatal error preventing Kea from running:

Removing the socket file allows Kea to start (rm /tmp/kea4-ctrl-socket.lock).