Revert "Cycles: Make use of maximum concurrent compilations on Metal"

This reverts commit 63d3fc2dcb, because it
causes a build error on the buildbot.

Ref #109655

intern/cycles/device/metal/kernel.mm

@@ -15,6 +15,9 @@
 
 CCL_NAMESPACE_BEGIN
 
+/* limit to 2 MTLCompiler instances */
+int max_mtlcompiler_threads = 2;
+
 const char *kernel_type_as_string(MetalPipelineType pso_type)
 {
   switch (pso_type) {
@@ -289,21 +292,6 @@ void ShaderCache::load_kernel(DeviceKernel device_kernel,
     /* create compiler threads on first run */
     thread_scoped_lock lock(cache_mutex);
     if (compile_threads.empty()) {
-      /* Limit to 2 MTLCompiler instances by default. In macOS >= 13.3 we can query the upper
-       * limit. */
-      int max_mtlcompiler_threads = 2;
-
-#  pragma clang diagnostic push
-#  pragma clang diagnostic ignored "-Wobjc-method-access"
-      /* Note: Disable warning for missing method when building on older OS's. Compiled code will
-       * still work correctly when run on a system with the API available. */
-      if (@available(macOS 13.3, *)) {
-        /* Subtract one to avoid contention with the real-time GPU module. */
-        max_mtlcompiler_threads = max(2, [mtlDevice maximumConcurrentCompilationTaskCount] - 1);
-      }
-#  pragma clang diagnostic pop
-
-      metal_printf("Spawning %d Cycles kernel compilation threads\n", max_mtlcompiler_threads);
       for (int i = 0; i < max_mtlcompiler_threads; i++) {
         compile_threads.push_back(std::thread([&] { compile_thread_func(i); }));
       }