Use property AutoreleasePoolSupport in test

The SDK also set the RuntimeHostConfigurationOption item.
So setting in this project results in multiple copies of the same item.

I'm not sure if this causes a problem with any currently supported
configuration of .NET, but it is detectable when compiling this test
with NativeAOT. ILC fails because multiple copies of the
`--appcontextswitch` flag are passed with the same key.

Author: AustinWise

src/tests/Interop/ObjectiveC/AutoReleaseTest/AutoReleaseTest.csproj

@@ -3,10 +3,8 @@
     <OutputType>Exe</OutputType>
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
     <CLRTestTargetUnsupported Condition="'$(TargetsOSX)' != 'true' and '$(TargetsiOS)' != 'true' and '$(TargetstvOS)' != 'true'">true</CLRTestTargetUnsupported>
+    <AutoreleasePoolSupport>true</AutoreleasePoolSupport>
   </PropertyGroup>
-  <ItemGroup>
-    <RuntimeHostConfigurationOption Include="System.Threading.Thread.EnableAutoreleasePool" Value="true" Trim="true" />
-  </ItemGroup>
   <ItemGroup>
     <Compile Include="*.cs" />
   </ItemGroup>