Troubles with MemoryDiagnoserTests

[AndreyAkinshin]

Subject: https://ci.appveyor.com/project/PerfDotNet/benchmarkdotnet/build/0.9.7.11/tests

@mattwarren, can you take a look?

[mattwarren]

yeah, np

[adamsitnik]

We no longer test ETW based Diagnoser, so the problems whatever they were are gone ;)