In xgboost 1.6, support for older GPU architectures was removed (dmlc/xgboost#7767).
This PR updates the instance types used in our xgboost-ray gpu release tests to use Volta GPUs instead of Kepler GPUs so that xgboost-ray can run successfully with xgboost v1.6.
Closes#24048
Instead of wrapping the whole training run in a remote call, we only query the files on the node in a remote call. XGBoost-Ray is then started from the local node.
