submodule clone comments changed to be more descriptive

test/distrib/cpp/run_distrib_test.sh

...ockerfile/grpc_check_generated_pb_files/check_pb_files.sh

...ckerfile/interoptest/grpc_interop_csharp/build_interop.sh

...e/interoptest/grpc_interop_csharpcoreclr/build_interop.sh

.../dockerfile/interoptest/grpc_interop_cxx/build_interop.sh

...ockerfile/interoptest/grpc_interop_http2/build_interop.sh

...dockerfile/interoptest/grpc_interop_node/build_interop.sh

.../dockerfile/interoptest/grpc_interop_php/build_interop.sh

...dockerfile/interoptest/grpc_interop_php7/build_interop.sh

...ckerfile/interoptest/grpc_interop_python/build_interop.sh

...dockerfile/interoptest/grpc_interop_ruby/build_interop.sh

...s_test/grpc_interop_stress_csharp/build_interop_stress.sh

...ress_test/grpc_interop_stress_cxx/build_interop_stress.sh

...tress_test/grpc_interop_stress_go/build_interop_stress.sh

...ess_test/grpc_interop_stress_java/build_interop_stress.sh

...ess_test/grpc_interop_stress_node/build_interop_stress.sh

...ress_test/grpc_interop_stress_php/build_interop_stress.sh

...s_test/grpc_interop_stress_python/build_interop_stress.sh

...ess_test/grpc_interop_stress_ruby/build_interop_stress.sh

tools/run_tests/dockerize/docker_run.sh