[SPARK-29188][PYTHON][FOLLOW-UP] Explicitly disable Arrow execution for all test of toPandas empty types

[HyukjinKwon]

What changes were proposed in this pull request?

Another followup of 4398dfa

I missed two more tests added:

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ERROR [0.133s]: test_to_pandas_from_mixed_dataframe (pyspark.sql.tests.test_dataframe.DataFrameTests)
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Traceback (most recent call last):
  File "/home/jenkins/python/pyspark/sql/tests/test_dataframe.py", line 617, in test_to_pandas_from_mixed_dataframe
    self.assertTrue(np.all(pdf_with_only_nulls.dtypes == pdf_with_some_nulls.dtypes))
AssertionError: False is not true
======================================================================
ERROR [0.061s]: test_to_pandas_from_null_dataframe (pyspark.sql.tests.test_dataframe.DataFrameTests)
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Traceback (most recent call last):
  File "/home/jenkins/python/pyspark/sql/tests/test_dataframe.py", line 588, in test_to_pandas_from_null_dataframe
    self.assertEqual(types[0], np.float64)
AssertionError: dtype('O') != <class 'numpy.float64'>
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Why are the changes needed?

To make the test independent of default values of configuration.

Does this PR introduce any user-facing change?

No.

How was this patch tested?

Manually tested and Jenkins should test.

[SparkQA]

Test build #116896 has finished for PR 27250 at commit 8a299fb.

• This patch passes all tests.
• This patch merges cleanly.
• This patch adds no public classes.

[HyukjinKwon]

Merged to master. (this is the same change as previous)

[dongjoon-hyun]

+1, late LGTM.