Revert "Add FormatterServices.GetUninitializedObject, partial for #8133"

src/System.Runtime/ref/System.Runtime.cs

@@ -3054,13 +3054,6 @@ public StructLayoutAttribute(System.Runtime.InteropServices.LayoutKind layoutKin
         public System.Runtime.InteropServices.LayoutKind Value { get { return default(System.Runtime.InteropServices.LayoutKind); } }
     }
 }
-namespace System.Runtime.Serialization
-{
-    public static partial class FormatterServices
-    {
-        public static Object GetUninitializedObject(Type type) { return default(Object); }
-    }
-}
 namespace System.Runtime.Versioning
 {
     [System.AttributeUsageAttribute((System.AttributeTargets)(1), AllowMultiple = false, Inherited = false)]

src/System.Runtime/tests/System.Runtime.Tests.csproj

@@ -65,7 +65,6 @@
     <Compile Include="System\Runtime\CompilerServices\ConditionalWeakTableTests.cs" />
     <Compile Include="System\Runtime\CompilerServices\StrongBoxTests.cs" />
     <Compile Include="System\Runtime\CompilerServices\RuntimeHelpersTests.cs" />
-    <Compile Include="System\Runtime\Serialization\FormatterServices.cs" />
     <Compile Include="System\SByteTests.cs" />
     <Compile Include="System\SingleTests.cs" />
     <Compile Include="System\StringTests.cs" />