Fix for sampling error in NumPy v1.9 [SPARK-3995][PYSPARK]

Change maximum value for default seed during RDD sampling so that it is strictly less than 2 ** 32. This prevents a bug in the most recent version of NumPy, which cannot accept random seeds above this bound.

Adds an extra test that uses the default seed (instead of setting it manually, as in the docstrings).

@mengxr