Add Python cloud prod gen interop command

tools/gce_setup/grpc_docker.sh

@@ -1041,6 +1041,19 @@ grpc_interop_gen_python_cmd() {
   echo $the_cmd
 }
 
+# constructs the full dockerized python interop test cmd.
+#
+# call-seq:
+#   flags= .... # generic flags to include the command
+#   cmd=$($grpc_gen_test_cmd $flags)
+grpc_cloud_prod_gen_python_cmd() {
+  local cmd_prefix="sudo docker run grpc/python bin/bash -l -c"
+  local gfe_flags=$(_grpc_prod_gfe_flags)
+  local env_prefix="SSL_CERT_FILE=/cacerts/roots.pem"
+  local the_cmd="$cmd_prefix '$env_prefix python -B -m interop.client --use_tls $gfe_flags $@'"
+  echo $the_cmd
+}
+
 # constructs the full dockerized python service_account auth interop test cmd.
 #
 # call-seq: