Use InvariantCulture for generated log file name in FileLogger ctor
Use InvariantCulture for generated log file name in FileLogger ctor

Fixes [AB#1433709](https://devdiv.visualstudio.com/DevDiv/_workitems/edit/1433709)

shyamnamboodiripad/roslyn,CyrusNajmabadi/roslyn,mavasani/roslyn,mavasani/roslyn,mavasani/roslyn,sharwell/roslyn,bartdesmet/roslyn,weltkante/roslyn,diryboy/roslyn,CyrusNajmabadi/roslyn,diryboy/roslyn,shyamnamboodiripad/roslyn,jasonmalinowski/roslyn,weltkante/roslyn,diryboy/roslyn,sharwell/roslyn,bartdesmet/roslyn,KevinRansom/roslyn,jasonmalinowski/roslyn,CyrusNajmabadi/roslyn,bartdesmet/roslyn,shyamnamboodiripad/roslyn,KevinRansom/roslyn,dotnet/roslyn,dotnet/roslyn,sharwell/roslyn,jasonmalinowski/roslyn,weltkante/roslyn,dotnet/roslyn,KevinRansom/roslyn