Remove unused conda packages before running BaseOnPython xgboost tests.

Signed-off-by: sfc-gh-mvashishtha <mahesh.vashishtha@snowflake.com>

Author: sfc-gh-mvashishtha

.github/workflows/ci.yml

@@ -176,6 +176,10 @@ jobs:
         run: |
           # TODO(https://github.com/modin-project/modin/issues/5194): Uncap xgboost
           # when we use collective instead of rabit.
+          # Per the thread https://github.com/conda-forge/miniforge/issues/513,
+          # remove unused conda packages and caches to avoid `Found incorrect
+          # download: joblib` error from mamba.
+          mamba clean --all
           mamba install "xgboost>=1.7.1,<2.0.0" scikit-learn -c conda-forge
           python -m pytest modin/tests/experimental/xgboost/test_default.py --execution=${{ matrix.execution }}
       - run: python -m pytest -n 2 modin/tests/core/storage_formats/base/test_internals.py --execution=${{ matrix.execution }}