Merge pull request #5402 from sreecha/stress_test_scripts

test/cpp/interop/metrics_client.cc

test/cpp/util/metrics_server.cc

tools/dockerfile/grpc_interop_stress_cxx/Dockerfile

...ockerfile/grpc_interop_stress_cxx/build_interop_stress.sh

tools/gcp/stress_test/run_client.py

tools/gcp/stress_test/run_server.py

tools/gcp/stress_test/stress_test_utils.py

tools/gcp/utils/big_query_utils.py

tools/gcp/utils/kubernetes_api.py

tools/jenkins/build_interop_stress_image.sh

tools/run_tests/stress_test/run_stress_tests_on_gke.py