COMException when generating ETW Log for benchmark

Just posting this here for visibility as it's the same problem as microsoft/perfview#1723.

I'm seeing COMExceptions when trying to generate an ETW trace for a benchmark.

The exception is
```
Unhandled exception. System.Runtime.InteropServices.COMException (0x800700AA): The requested resource is in use. (0x800700AA)
at System.Runtime.InteropServices.Marshal.ThrowExceptionForHR(Int32 errorCode)
at Microsoft.Diagnostics.Tracing.Session.TraceEventSession.EnableKernelProvider(Keywords flags, Keywords stackCapture)
at BenchmarkDotNet.Diagnostics.Windows.KernelSession.EnableProviders()
at BenchmarkDotNet.Diagnostics.Windows.EtwProfiler.Start(DiagnoserActionParameters parameters)
at BenchmarkDotNet.Diagnostics.Windows.EtwProfiler.Handle(HostSignal signal, DiagnoserActionParameters parameters)
at BenchmarkDotNet.Diagnosers.CompositeDiagnoser.Handle(HostSignal signal, DiagnoserActionParameters parameters)
```