get_gbt_model_from_xgboost should be replaced by call to daal4py library

[eduand-alvarez]

The daal_xgb_model.py module has a function called get_gbt_model_from_xgboost. This was presumably added because it wasn't available in the daal4py library. For simplicity of code, it should be removed and replaced by the call to the daal4py lib.

import daal4py as d4p d4p.get_gbt_model_from_xgboost()