As a part of SPM-4106, we split DocumentSources into QO and QE parts. Memory tracking is only relevant to the QE part, so we should move the relevant data members to the corresponding agg::Stage subclass.

If stages have unit tests that require alternative maxAllowedMemoryUsageBytes settings, this can be done by using RAIIServerParameterControllerForTest scope object instead of passing it as parameter.

As a part of this ticket, we need to move the remains memory-tracking from QO to QE stage (for instance from DocumentSourceGroup and DocumentSourceSort).