Add script in server installation

Following:

https://github.com/DIRACGrid/DIRAC/security/advisories/GHSA-v897-f98g-jpxw

a new scipt should be added to the server installation of the WebApp:

cat /opt/dirac/runit/Web/WebApp/control/t

#!/bin/bash

echo "Killing the webapp for good" pkill -9 -f dirac-webapp-run

This should be added in the scripts for deployment.