[DRT] Fix DrtFlow failures

[rladuca]

DrtFlow()
OS: 2k8R2
Log Link: See Test Results Emails

[grubioe]

@ojhad - can you look into this one? Thanks

[ojhad]

Closing this issue because failure is only happening on an OS that is not supported by .NET Core 3.0:
https://github.com/dotnet/core/blob/master/release-notes/3.0/3.0-supported-os.md