Small cleanup to the proxy dmatrix.

[trivialfis]

• Remove the auto-dispatch for CUDA methods.

Ref #11088

[Copilot]

Pull Request Overview

This PR cleans up the proxy DMatrix implementation by removing auto-dispatch for CUDA methods and standardizing method naming conventions. The changes focus on making the API more explicit about whether methods handle CPU or GPU data.

• Renamed several methods to use consistent naming patterns (e.g., SetArrayData → SetArray, SetCUDAArray → SetCudaArray)
• Removed auto-dispatch logic that automatically determined whether to use CUDA columnar or array methods
• Added explicit CUDA method stubs when CUDA support is not available
• Updated copyright years and cleaned up includes

Reviewed Changes

Copilot reviewed 13 out of 13 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
src/data/proxy_dmatrix.h	Updated method signatures and documentation, removed auto-dispatch logic
src/data/proxy_dmatrix.cc	Renamed host methods and added CUDA stubs for non-CUDA builds
src/data/proxy_dmatrix.cu	Renamed CUDA methods to match new naming convention
src/c_api/c_api.cc	Updated calls to use renamed proxy DMatrix methods
src/c_api/c_api.cu	Updated CUDA API calls to use renamed methods
tests/cpp/predictor/test_predictor.cc	Updated test calls to use renamed methods
tests/cpp/predictor/test_gpu_predictor.cu	Updated GPU test calls and copyright year
tests/cpp/predictor/test_cpu_predictor.cc	Updated CPU test calls and copyright year
tests/cpp/gbm/test_gbtree.cu	Updated test calls, copyright year, and cleaned imports
tests/cpp/gbm/test_gbtree.cc	Updated test calls and copyright year
tests/cpp/gbm/test_gblinear.cu	Updated copyright year only
tests/cpp/data/test_proxy_dmatrix.cu	Updated test calls, copyright year, and cleaned imports
tests/cpp/data/test_proxy_dmatrix.cc	Updated test calls, copyright year, and cleaned imports

[trivialfis]

cc @rongou .