update cloudbuild to pull the PR changes

Author: Pulkit0110

cloudbuild/run_zonal_tests.sh

@@ -6,6 +6,7 @@ sudo apt-get update && sudo apt-get install -y git python3-pip python3-venv
 # Clone the repository and checkout the specific commit from the build trigger.
 git clone https://github.com/googleapis/python-storage.git
 cd python-storage
+git fetch origin "refs/pull/${_PR_NUMBER}/head"
 git checkout ${COMMIT_SHA}
 
 

cloudbuild/zb-system-tests-cloudbuild.yaml

@@ -68,7 +68,7 @@ steps:
         # Execute the script on the VM via SSH.
         # Capture the exit code to ensure cleanup happens before the build fails.
         set +e
-        gcloud compute ssh ${_VM_NAME} --zone=${_ZONE} --internal-ip --ssh-key-file=/workspace/.ssh/google_compute_engine --command="ulimit -n {_ULIMIT}; COMMIT_SHA=${COMMIT_SHA} _ZONAL_BUCKET=${_ZONAL_BUCKET} bash run_zonal_tests.sh"
+        gcloud compute ssh ${_VM_NAME} --zone=${_ZONE} --internal-ip --ssh-key-file=/workspace/.ssh/google_compute_engine --command="ulimit -n {_ULIMIT}; COMMIT_SHA=${COMMIT_SHA} _ZONAL_BUCKET=${_ZONAL_BUCKET} _PR_NUMBER=${_PR_NUMBER} bash run_zonal_tests.sh"
         EXIT_CODE=$?
         set -e