Test old Lowering flow for op_ceiling.py (#7271)

Summary:

- Added code to ensure that the legacy code was being called the same way as seen in linear.py

Reviewed By: mcr229

Differential Revision: D66739374

backends/xnnpack/test/ops/ceil.py

@@ -20,17 +20,22 @@ def forward(self, x):
             return z
 
     def _test_ceil(self, inputs):
-        (
-            Tester(self.Ceil(), inputs)
-            .export()
-            .check_count({"torch.ops.aten.ceil.default": 1})
-            .to_edge_transform_and_lower()
-            .check_count({"torch.ops.higher_order.executorch_call_delegate": 1})
-            .check_not(["executorch_exir_dialects_edge__ops_aten_ceil_default"])
-            .to_executorch()
-            .serialize()
-            .run_method_and_compare_outputs()
-        )
+        for legacy_mode in (True, False):
+            tester = Tester(self.Ceil(), inputs)
+            tester.export()
+            tester.check_count({"torch.ops.aten.ceil.default": 1})
+
+            if legacy_mode:
+                tester.to_edge()
+                tester.partition()
+            else:
+                tester.to_edge_transform_and_lower()
+
+            tester.check_count({"torch.ops.higher_order.executorch_call_delegate": 1})
+            tester.check_not(["executorch_exir_dialects_edge__ops_aten_ceil_default"])
+            tester.to_executorch()
+            tester.serialize()
+            tester.run_method_and_compare_outputs()
 
     def test_fp16_ceil(self):
         inputs = (