[CI] Set up test analytics for CPU Python tests (dmlc#8333)

* [CI] Set up test analytics for CPU Python tests

* Install test collector

Author: hcho3

tests/buildkite/test-python-cpu.sh

@@ -11,4 +11,6 @@ buildkite-agent artifact download "python-package/dist/*.whl" . --step build-cud
 buildkite-agent artifact download "xgboost" . --step build-cpu
 chmod +x ./xgboost
 
+export BUILDKITE_ANALYTICS_TOKEN=$(get_aws_secret buildkite/test_analytics/cpu)
+set_buildkite_env_vars_in_container
 tests/ci_build/ci_build.sh cpu docker tests/ci_build/test_python.sh cpu

tests/ci_build/Dockerfile.cpu

@@ -37,7 +37,9 @@ RUN git clone -b v1.49.1 https://github.com/grpc/grpc.git \
 
 # Create new Conda environment
 COPY conda_env/cpu_test.yml /scripts/
-RUN mamba env create -n cpu_test --file=/scripts/cpu_test.yml
+RUN mamba env create -n cpu_test --file=/scripts/cpu_test.yml && \
+    mamba clean --all && \
+    conda run --no-capture-output -n cpu_test pip install buildkite-test-collector
 
 # Install lightweight sudo (not bound to TTY)
 RUN set -ex; \