Use the new more efficient .NET 9 Lock type (#18015)

src/Umbraco.Web.Common/ModelsBuilder/InMemoryAuto/CollectibleRuntimeViewCompiler.cs

@@ -20,7 +20,7 @@ namespace Umbraco.Cms.Web.Common.ModelsBuilder.InMemoryAuto;
 
 internal class CollectibleRuntimeViewCompiler : IViewCompiler
 {
-    private readonly object _cacheLock = new object();
+    private readonly Lock _cacheLock = new();
     private readonly Dictionary<string, CompiledViewDescriptor> _precompiledViews;
     private readonly ConcurrentDictionary<string, string> _normalizedPathCache;
     private readonly IFileProvider _fileProvider;

src/Umbraco.Web.Common/ModelsBuilder/InMemoryAuto/InMemoryModelFactory.cs

@@ -162,7 +162,7 @@ namespace Umbraco.Cms.Web.Common.ModelsBuilder.InMemoryAuto
         public Assembly? CurrentModelsAssembly { get; private set; }
 
         /// <inheritdoc />
-        public object SyncRoot { get; } = new object();
+        public object SyncRoot { get; } = new();
 
         private UmbracoServices UmbracoServices => _umbracoServices.Value;