[Hardware] Replace torch.cuda.synchronize() api with torch.accelerator.synchronize (#36085)

Signed-off-by: Kunshang Ji <kunshang.ji@intel.com>

tests/distributed/test_custom_all_reduce.py

@@ -48,7 +48,7 @@ def graph_allreduce(
         data = torch.zeros(1)
         data = data.to(device=device)
         torch.distributed.all_reduce(data, group=group)
-        torch.cuda.synchronize()
+        torch.accelerator.synchronize()
         del data
 
         # we use the first group to communicate once
@@ -68,7 +68,7 @@ def graph_allreduce(
                     inp2 = torch.randint(
                         1, 16, (sz,), dtype=dtype, device=torch.cuda.current_device()
                     )
-                    torch.cuda.synchronize()
+                    torch.accelerator.synchronize()
                     graph = torch.cuda.CUDAGraph()
                     with torch.cuda.graph(graph, stream=graph_capture_context.stream):
                         for i in range(num_communication):