[Performance] Use forward_native for Conv3dLayer and add UT (#8375)

What this PR does / why we need it?
switch Ascend conv3d forward_oot to use forward_native and  add ut

Does this PR introduce any user-facing change?
No

How was this patch tested?
by CI

---------

Signed-off-by: zouyizhou <zouyizhou@huawei.com>

tests/ut/_310p/ops/test_conv_310.py

@@ -0,0 +1,35 @@
+from unittest.mock import MagicMock, patch
+
+import pytest
+import torch
+from vllm.config import set_current_vllm_config
+from vllm.model_executor.layers.conv import Conv3dLayer
+
+from vllm_ascend._310p.ops.conv import AscendConv3dLayer310
+
+
+@pytest.fixture(autouse=True)
+def default_vllm_config():
+    mock_config = MagicMock()
+    mock_config.compilation_config.custom_ops = ["all"]
+    with set_current_vllm_config(mock_config):
+        yield mock_config
+
+
+def test_conv3d_310_forward_oot_uses_forward_native():
+    layer = AscendConv3dLayer310(
+        in_channels=2,
+        out_channels=4,
+        kernel_size=(2, 2, 2),
+        stride=(2, 2, 2),
+        bias=True,
+        params_dtype=torch.float32,
+    )
+    x = torch.randn(1, 2, 4, 4, 4, dtype=torch.float32)
+    expected = torch.randn(1, 4, 2, 2, 2, dtype=torch.float32)
+
+    with patch.object(Conv3dLayer, "forward_native", autospec=True, return_value=expected) as mock_forward_native:
+        out = layer.forward_oot(x)
+
+    mock_forward_native.assert_called_once_with(layer, x)
+    assert out is expected