Download test resources for continuous jobs

Author: busunkim96

.kokoro/continuous.cfg

@@ -10,6 +10,9 @@ action {
 # Download trampoline resources.
 gfile_resources: "/bigstore/cloud-devrel-kokoro-resources/trampoline"
 
+# Download resources for system tests (service account key, etc.)
+gfile_resources: "/bigstore/cloud-devrel-kokoro-resources/google-cloud-python"
+
 # Use the trampoline script to run in docker.
 build_file: "google-cloud-python-happybase/.kokoro/trampoline.sh"