Improve Entitlements service, set "group" as default DOMAIN property value (GONRG-4129)

Type of change

• Bug Fix
• Feature

https://jiraeu.epam.com/browse/GONRG-4129

Does this introduce a change in the core logic?

• [YES]

Does this introduce a change in the cloud provider implementation, if so which cloud?

• AWS
• Azure
• GCP
• IBM

Does this introduce a breaking change?

• [YES]

What is the current behavior?

Improve Entitlements service, set "group" as default DOMAIN property value and fix README

• Added config property
• Added usage of the new property for groups. Currently, the change of domain only added for JDBC module. In other providers, the descriptor is the same with DOMAIN property