Unify DART SHAP forwarding #14824

Job	Run time
Build libxgboost4j.so targeting glibc 2.17 (arch x86_64, runner linux-amd64-cpu)	2m 9s
Configure variables for CI	8s
Build libxgboost4j.dylib for MacOS (Apple Silicon)	34s
Build and test JVM packages (windows-latest)	8m 50s
Build libxgboost4j.so targeting glibc 2.17 (arch aarch64, runner linux-arm64-cpu)	2m 18s
Build and test JVM packages (macos-15-intel)	12m 49s
Build libxgboost4j.dylib for MacOS (Intel)	1m 38s
Build libxgboost4j.so with CUDA	5m 9s
Build and test JVM packages (Linux, Scala 2.13)	5m 26s
Build and test JVM packages (Linux, Scala 2.12)	10m 39s
Test JVM packages with CUDA (Scala 2.13)	8m 13s
Test JVM packages with CUDA (Scala 2.12)	8m 9s
Deploy JVM packages to S3 (cpu, Scala 2.12)	56s
Deploy JVM packages to S3 (gpu, Scala 2.12)	2m 59s
Deploy JVM packages to S3 (gpu, Scala 2.13)	2m 55s
Deploy JVM packages to S3 (cpu, Scala 2.13)	51s
	1h 13m 43s

Provide feedback