Refactor regex string

Regex that is used in calculation of short system names. It is per environment, so the var that is needed for the regex moved to the group_vars inventory. E.g. in DEV env it will be ".dev.geant.private", in UAT and PROD - different.

requested review from @simone.spinelli

assigned to @Aleksandr.Kurbatov

merged

mentioned in commit 79ea50cf