Consistent logging and tracker handling for increment/decrement

We log DEBUG output and use GroupTracker inconsistently in Manager and in UserTracker.

Eg.
Manager.IncreaseTrackedResource(): only a single log output with DEBUG level
Manager.DecreaseTrackedResource(): multiple log statements, also handles the group tracker which is not the case with increments

This also affects UserTracker - logs&GroupTracker handling are different in increaseTrackedResource()/decreaseTrackedResource()