Use property AutoreleasePoolSupport in test (#76800)

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.

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>