Added new flags to solve no local C compiler bug in bazel

tools/internal_ci/linux/grpc_ubsan_on_foundry.sh

@@ -57,6 +57,9 @@ source tools/internal_ci/helper_scripts/prepare_build_linux_rc
   --copt=-fsanitize=undefined \
   --linkopt=-fsanitize=undefined \
   --crosstool_top=@com_github_bazelbuild_bazeltoolchains//configs/experimental/ubuntu16_04_clang/1.0/bazel_0.13.0/ubsan:toolchain \
+  --action_env=BAZEL_DO_NOT_DETECT_CPP_TOOLCHAIN=1 \
+  --extra_toolchains=@com_github_bazelbuild_bazeltoolchains//configs/ubuntu16_04_clang/1.0/bazel_0.13.0/cpp:cc-toolchain-clang-x86_64-default \
+  --extra_execution_platforms=@com_github_bazelbuild_bazeltoolchains//configs/ubuntu16_04_clang/1.0:rbe_ubuntu1604 \
   -- //test/... || FAILED="true"
 
 # Sleep to let ResultStore finish writing results before querying