Fix export config in tests

Summary:
It doesn't look correct that want to export models with one config but test the export with a different one.

This diff is to ensure using canonical config for both export and tests.

TODO: Rerun the existing tests failed with msg about missing required positional arguments. It's likely related to the params lifting and unlifting. Will figure it out.

Differential Revision: D48018569

fbshipit-source-id: 1685533affdd83c0ac00af1150e20cb15715ba4f

Author: guangy10

examples/export/test/test_export.py

@@ -8,7 +8,7 @@
 
 import torch
 
-from executorch.examples.export.utils import _EDGE_COMPILE_CONFIG
+from executorch.examples.export.utils import _CAPTURE_CONFIG, _EDGE_COMPILE_CONFIG
 from executorch.examples.models import MODEL_NAME_TO_MODEL
 
 
@@ -18,8 +18,7 @@ def _assert_eager_lowered_same_result(
     ):
         import executorch.exir as exir
 
-        capture_config = exir.CaptureConfig(enable_dynamic_shape=False)
-        edge_model = exir.capture(eager_model, example_inputs, capture_config).to_edge(
+        edge_model = exir.capture(eager_model, example_inputs, _CAPTURE_CONFIG).to_edge(
             _EDGE_COMPILE_CONFIG
         )