[QE](7.0.z) User should be informed when switching between JDBC and journal store in transactions subsystem

Precondition: 'Use journal store' or 'Use JDBC store' was previously set to true.
When enabling other type of store, user is not informed about the fact, that only one of those can be set and the previously enabled store is disabled and the new store is enabled without notification. User should be definitely informed about this.