Build MG C++ tests in libcuml-tests

[bdice]

Builds the multi-GPU C++ tests as part of the libcuml-tests conda package so they use the sccache build infrastructure, and removes the separate MG build job added in #8683. MG tests are excluded from the single-GPU ctest run.

Closes #8735.

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📥 Commits

Reviewing files that changed from the base of the PR and between 9af68cf and 8c08424.

📒 Files selected for processing (6)

• .github/workflows/pr.yaml
• .github/workflows/test.yaml
• ci/build_mg_cpp_tests.sh
• ci/test_cpp.sh
• conda/recipes/libcuml/recipe.yaml
• dependencies.yaml

💤 Files with no reviewable changes (4)

• .github/workflows/test.yaml
• dependencies.yaml
• .github/workflows/pr.yaml
• ci/build_mg_cpp_tests.sh

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📝 Summary

Summary by CodeRabbit

• Tests
  • C++ multi-GPU tests are now built through the library’s package build. The dedicated multi-GPU test jobs have been removed from the pull request and test workflows, and matching tests are excluded from the remaining C++ test command.

Walkthrough

The PR moves cpp-mgtests into the libcuml-tests package build and adds OpenMPI build and test requirements. It removes the dedicated MG C++ test CI job and build environment. The timed C++ test run excludes tests matching MG_.

Changes

MG C++ Test Build

Layer / File(s)	Summary
Package build and requirements conda/recipes/libcuml/recipe.yaml, dependencies.yaml	The libcuml build adds cpp-mgtests and OpenMPI host requirements. The separate build_cpp_mg_tests environment and dependency group are removed.
C++ test selection ci/test_cpp.sh	The timed C++ test run excludes tests matching ^MG_. The copyright notice is updated.
Dedicated CI build removal .github/workflows/pr.yaml, .github/workflows/test.yaml, ci/build_mg_cpp_tests.sh	The dedicated MG C++ test jobs, the pr-builder dependency, and the build script are removed.

Priority: ⬇️ Low

Estimated code review effort: 2 (Simple) | ~12 minutes

Change: Other

Merge Risk: ⚪ Minimal · up to 8c084

This change moves multi-GPU C++ test builds into the libcuml-tests package and keeps them out of the single-GPU test run. No concrete merge-blocking risk was identified.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly describes the main change: building multi-GPU C++ tests in the libcuml-tests package.
Description check	✅ Passed	The description summarizes the implementation, explains the related CI changes, and links issue #8735 with a closing keyword. It meets the required Summary section.
Linked Issues check	✅ Passed	Issue #8735 requires building multi-GPU C++ tests through libcuml-tests so they can use sccache infrastructure. conda/recipes/libcuml/recipe.yaml builds cpp-mgtests in the package build, exposes…
Out of Scope Changes check	✅ Passed	The workflow and script removals replace the separate MG build job with the package build required by issue #8735. Excluding MG tests from the single-GPU run and removing the obsolete MG-build environ…
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check. Docstring coverage is scoped to functions touched by this diff. Analyzed 0 functions across 1…

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[chyunsu3]

/merge