Set RETRIES variable for login on iso

[sandzwerg]

The ISO version of fedIPA will try 100 times to download the stage2 before you have the chance to login & debug. This takes a lot of time and most often if it does not work in the first couple of tries it's unlikely to work in later ones. This https://github.com/search?q=repo%3Adracutdevs%2Fdracut%20RETRIES&type=code suggests that setting the value of RETRIES to a lower number would decrease the tries from the default of 100.