cleanup and speedup of sanity tests

templates/tools/dockerfile/clang_format.include

...es/tools/dockerfile/grpc_clang_format/Dockerfile.template

templates/tools/dockerfile/test/sanity/Dockerfile.template

tools/distrib/check_nanopb_output.sh

tools/distrib/clang_format_code.sh

tools/dockerfile/grpc_clang_format/Dockerfile

...ckerfile/grpc_clang_format/clang_format_all_the_things.sh

tools/dockerfile/test/sanity/Dockerfile

tools/run_tests/dockerize/build_docker_and_run_tests.sh

tools/run_tests/run_tests.py