Suppress traceback for model tests

[vchan]

Per the discussion with @izeigerman, the current stack trace included with model test failures is not very useful.

Old failure:

F
======================================================================
FAIL: test_example_full_model (/Users/izeigerman/github/tmp/tests/test_example_full_model.yaml:1)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/Users/izeigerman/github/sqlmesh/sqlmesh/core/test.py", line 158, in runTest
    self.assert_equal(expected_df, actual_df)
  File "/Users/izeigerman/github/sqlmesh/sqlmesh/core/test.py", line 135, in assert_equal
    raise e
  File "/Users/izeigerman/github/sqlmesh/sqlmesh/core/test.py", line 124, in assert_equal
    pd.testing.assert_frame_equal(
  File "/Users/izeigerman/github/sqlmesh/.venv/lib/python3.9/site-packages/pandas/_testing/asserters.py", line 1343, in assert_frame_equal
    assert_series_equal(
  File "/Users/izeigerman/github/sqlmesh/.venv/lib/python3.9/site-packages/pandas/_testing/asserters.py", line 1108, in assert_series_equal
    _testing.assert_almost_equal(
  File "pandas/_libs/testing.pyx", line 52, in pandas._libs.testing.assert_almost_equal
  File "pandas/_libs/testing.pyx", line 167, in pandas._libs.testing.assert_almost_equal
  File "/Users/izeigerman/github/sqlmesh/.venv/lib/python3.9/site-packages/pandas/_testing/asserters.py", line 679, in raise_assert_detail
    raise AssertionError(msg)
AssertionError: Data differs
- {'item_id': 1, 'num_orders': 3}
?                              ^

+ {'item_id': 1, 'num_orders': 2}
?                              ^

New failure:

F
======================================================================
FAIL: test_example_full_model (/Users/izeigerman/github/tmp/tests/test_example_full_model.yaml:1)
----------------------------------------------------------------------
AssertionError: Data differs
- {'item_id': 1, 'num_orders': 3}
?                              ^

+ {'item_id': 1, 'num_orders': 2}
?                              ^

[izeigerman]

should each tuple member be t.Optional instead of a tuple of Nones? Otherwise this signature claims that either all items must be present or none of them. If this is the expectation, then please ignore my comment.

[vchan]

This is the expectation. This signature matches the parent function's signature.