Fix System.IO.FileSystem.DisabledFileLocking.Tests with NativeAOT (#72311)

#72310 tracks supporting runtimeconfig.template.json. Use the MSBuild property instead as that one works.

Author: MichalStrehovsky

src/libraries/System.IO.FileSystem/tests/DisabledFileLockingTests/System.IO.FileSystem.DisabledFileLocking.Tests.csproj

@@ -33,4 +33,7 @@
   <ItemGroup>
     <ProjectReference Include="$(CommonTestPath)StreamConformanceTests\StreamConformanceTests.csproj" />
   </ItemGroup>
+  <ItemGroup>
+    <RuntimeHostConfigurationOption Include="System.IO.DisableFileLocking" Value="true" />
+  </ItemGroup>
 </Project>