Some python and notebook versions of examples have diverged

[eordentlich]

Describe the bug
Not sure it is the case for all examples, but for the mortgage ETL + XGBoost example there are some non-trivial discrepancies. Example:
python script has udfs: https://github.com/NVIDIA/spark-rapids-examples/blob/main/examples/XGBoost-Examples/mortgage/python/com/nvidia/spark/examples/mortgage/etl.py#L22-L23
while the notebook(s) implement these using Spark SQL directly:
https://github.com/NVIDIA/spark-rapids-examples/blob/main/examples/XGBoost-Examples/mortgage/notebooks/python/MortgageETL.ipynb?short_path=2af22cf#L454-L478
There are some other differences. Looks like the scripts may be lagging the notebooks.

Steps/Code to reproduce bug
N/A

Expected behavior
Notebooks and python script versions should ideally be aligned (or at least documented why they don't).

Environment details (please complete the following information)
N/A

[GaryShen2008]

@nvliyuan Do you remember who wrote these examples? I can't recall the reason, but there should be.

[nvliyuan]

Yes, the same example with different implementations should keep the same logic, will draft a pr to fix it.