Removing using System.Runtime.CompilerServices directive mistakenly added by 11903086f8d (Bug 1475: Mask out password in .NET assembly output log)

+ The same directive removed from Tests project

Source commit: a8bb2bf276f53323c39d89d1465e964d789d5896

dotnet/properties/AssemblyInfo.cs

@@ -1,6 +1,5 @@
 using System;
 using System.Reflection;
-using System.Runtime.CompilerServices;
 using System.Runtime.InteropServices;
 
 // General Information about an assembly is controlled through the following