suricata: Remove PID file on stop

Force the initscript to remove the PID file when calling "stop" section.

If suricata crashes during startup, the PID file still remains and the service
cannot be started anymore until the file has been deleted.

Now when calling "stop" or "restart" the PID file will be deleted and the service
can be used again.

Fixes #12067.

Signed-off-by: Stefan Schantl <stefan.schantl@ipfire.org>
Signed-off-by: Arne Fitzenreiter <arne_f@ipfire.org>