* [jvm-packages] fix executor crashing issue when transforming on xgboost4j-spark-gpu
the API XGBoosterSetParam is not thread-safe. Dring the phase of transforming,
XGBoost runs several transforming tasks at a time, and each of them will set
the "gpu_id" and "predictor" parameters, so if several tasks (multi-threads)
all XGBoosterSetParam simultaneously, it may cause the memory to be corrupted
and cause SIGSEGV.
This PR first get the booster from broadcast and set to the correct gpu_id
and predictor, and then all transforming taskes will use the same booster to
do the transforming.
a68580e2a7