[ci] Avoid fetching GTest with CMake. (#11828)

Author: trivialfis

.github/workflows/misc.yml

@@ -17,13 +17,17 @@ jobs:
   gtest-cpu-nonomp:
     name: Test Google C++ unittest (CPU Non-OMP)
     runs-on: ubuntu-latest
+    defaults:
+      run:
+        shell: bash -l {0}
     steps:
       - uses: actions/checkout@v4
         with:
           submodules: 'true'
-      - name: Install system packages
-        run: |
-          sudo apt-get install -y --no-install-recommends ninja-build
+      - uses: dmlc/xgboost-devops/actions/miniforge-setup@main
+        with:
+          environment-name: cpp_test
+          environment-file: ops/conda_env/cpp_test.yml
       - name: Build and test XGBoost
         run: bash ops/pipeline/build-test-cpu-nonomp.sh
 

ops/pipeline/build-test-cpu-nonomp.sh

@@ -10,7 +10,6 @@ cmake .. \
   -DUSE_OPENMP=OFF \
   -DHIDE_CXX_SYMBOLS=ON \
   -DGOOGLE_TEST=ON \
-  -DUSE_DMLC_GTEST=ON \
   -DENABLE_ALL_WARNINGS=ON \
   -DCMAKE_COMPILE_WARNING_AS_ERROR=OFF
 time ninja -v