Enable System.Runtime.Serialization.Xml test assembly for Mono on Windows (#34816)

Follow-up to #32592 (review).

Author: MaximLipnin

src/libraries/System.Runtime.Serialization.Xml/tests/AssemblyInfo.cs

@@ -3,7 +3,6 @@
     <TargetFrameworks>$(NetCoreAppCurrent)</TargetFrameworks>
   </PropertyGroup>
   <ItemGroup>
-    <Compile Include="AssemblyInfo.cs" />
     <Compile Include="$(TestSourceFolder)DataContractSerializerStressTests.cs" />
     <Compile Include="$(TestSourceFolder)SerializationTypes.cs" />
     <Compile Include="$(TestSourceFolder)SerializationTypes.RuntimeOnly.cs" />