Unstable counterexample test

[keyboardDrummer]

The test DatatypeObjectWithTwoDestructorsWhoseValuesAreEqual seems to fail sometimes.

https://github.com/dafny-lang/dafny/actions/runs/5998742793/job/16268642812?pr=4476

[xUnit.net 00:00:45.61]         --- End of stack trace from previous location ---
  Failed Microsoft.Dafny.LanguageServer.IntegrationTest.Various.CounterExampleTest.DatatypeObjectWithTwoDestructorsWhoseValuesAreEqual(optionSettings: Action`1 { Method = Void <OptionSettings>b__1_0(Microsoft.Dafny.DafnyOptions), Target = <>c { } }) [564 ms]
  Error Message:
   The collection was expected to contain a single element, but it was empty.