ci: nightly cleanup cleanup (googleapis#886)

* ci: nightly cleanup cleanup

* missing credentials

* nit

* Update run_samples_resource_cleanup.sh

* Update run_samples_resource_cleanup.sh

* Update run_samples_resource_cleanup.sh

* Update run_samples_resource_cleanup.sh

* try again

* try again

* nit

Author: stephaniewang526

.kokoro/nightly/samples.cfg

@@ -1,5 +1,8 @@
 # Format: //devtools/kokoro/config/proto/build.proto
 
+# Download secrets from Cloud Storage.
+gfile_resources: "/bigstore/cloud-devrel-kokoro-resources/java-docs-samples"
+
 # Configure the docker image for kokoro-trampoline.
 env_vars: {
   key: "TRAMPOLINE_IMAGE"

.kokoro/run_samples_resource_cleanup.sh

@@ -32,18 +32,6 @@ source ${scriptDir}/common.sh
 source ${KOKORO_GFILE_DIR}/secret_manager/java-bigquery-samples-secrets
 echo "********** Successfully Set All Environment Variables **********"
 
-# if GOOGLE_APPLICATION_CREDIENTIALS is specified as a relative path prepend Kokoro root directory onto it
-if [[ ! -z "${GOOGLE_APPLICATION_CREDENTIALS}" && "${GOOGLE_APPLICATION_CREDENTIALS}" != /* ]]; then
-    export GOOGLE_APPLICATION_CREDENTIALS=$(realpath ${KOKORO_GFILE_DIR}/secret_manager/${GOOGLE_APPLICATION_CREDENTIALS})
-fi
-
-# Activate service account
-gcloud auth activate-service-account \
-    --key-file="$GOOGLE_APPLICATION_CREDENTIALS" \
-    --project="$GOOGLE_CLOUD_PROJECT"
-
-mvn clean install -DskipTests=true
-
 # Move into the samples directory
 cd samples/snippets