Update restore from backup workflow

[irina060981]

We use not officially proposed way to backup, existdb official documentation suggests to use backrest - https://exist-db.org/exist/apps/doc/backup, but I was not able to find it

This not proper way gives the following problems:

• we need to startup existdb to be able to start restoring from backup, but it hangs the container
• that's why I was consulted to do the following workaround: I started up existd as a service and wait a minute to be sure that it is tarted up and doesn;t throw a error Connection refused

${EXIST_HOME}/bin/startup.sh &
sleep 1m

• and that's why I need to finish startup script with the following

exec tail -f /dev/null