fix failing DigitizationComparisonNew_test.py
Fix this failing new config comparison test by setting the ConfigFlags.Concurrency.NumConcurrentEvents
, whose behaviour was changed in !32970 (merged). This change is similar to 7eb91097.
This resolves ATLASSIM-4579.
Also correct the description string Simulation/Tests/DigitizationTests/test/test_DigitizationComparison.sh
.