Unblock CI for 25.04

[csadorf]

This PR addresses two issues that are currently blocking the cuML CI on the 25.04 release branch:

1. Out-of-memory (OOM) errors occurring in SVM tests on CUDA 11.8:

   • Several SVM-related tests, particularly test_svc_methods, are failing with OOM errors and segmentation faults
   • This only surfaces with CUDA 11.8 and is likely due to memory allocation patterns
   • As a temporary workaround, we skip these tests on CUDA 11.8 while the root cause is investigated

2. XGBoost test dependency compatibility:

   • XGBoost 3.0.0 has a known issue that manifests when using older NVIDIA drivers with recent CUDA toolkit versions (CUDA Driver Error with XGBoost 3.0.0 on CUDA 12.8 with Older Driver Versions dmlc/xgboost#11397)
   • To maintain stability, we constrain the XGBoost test dependency to versions < 3.0.0
   • This ensures consistent test behavior across different driver/toolkit combinations

We expect to remove the constraint on the xgboost version once the issue is resolved in a future xgboost release.

We expect to be able to address the SVM test issue by reducing its memory footprint (see #6514), however here we are taking a more conservative approach to ensure that the CI pipeline is stable.

The remaining failing CI job is optional, the issue is going to be addressed on branch-25.06.

[jakirkham]

Thanks Simon! 🙏

Please update the Conda recipes as well

[csadorf]

Thanks Simon! 🙏

Please update the Conda recipes as well

@jakirkham Xgboost is not a hard cuml dependency. It is currently not included in the conda build recipes. I am updating our test dependencies in the PR.

[jakirkham]

Thanks for clarifying Simon! 🙏

Ok looks good