fix: adds config file and shell script to run storage cloudbuild tests

[chalmerlowe]

Description

Partially Fixes #googleapis/google-cloud-python#16487

This PR is offered as starting point to enable cloudbuild tests for the Storage Team.
This mirrors a config and script that was in use in the split repo prior to migrating python-storage into the google-cloud-python monorepo.

I am not versed in all the nuances of how this needs to be configured. @chandra-siri and @chingor13 were instrumental in getting similar tests running in google-cloud-python.

I think these task apply, but as I said: not the expert.

• These samples need a new API enabled in testing projects to pass (let us know which ones)
• These samples need a new/updated env vars in testing projects set to pass (let us know which ones)
• Please merge this PR for me once it is approved

[gemini-code-assist]

Code Review

This pull request introduces a new CI/CD pipeline for zonal system tests, including a Cloud Build configuration and a helper shell script to run tests on a GCE VM. Feedback focuses on correcting the repository URL and directory paths to align with the current monorepo structure, as well as addressing potential issues with aggressive SSH key cleanup that could interfere with concurrent builds. Other recommendations include adding missing substitutions for better documentation, using a stable Debian image, simplifying service account scopes, and adding a shebang to the shell script.

[gemini-code-assist]

The directory paths include a main/ prefix (e.g., git sparse-checkout set main/storage, cd main/storage) which does not match the standard repository structure. In the monorepo, the storage component is located at the root level storage/.

Suggested change

	cd python-docs-samples
	git sparse-checkout set main/storage
	git fetch origin "refs/pull/${_PR_NUMBER}/head"
	git checkout ${COMMIT_SHA}
	cd main/storage
	cd google-cloud-python
	git sparse-checkout set storage
	git fetch origin "refs/pull/${_PR_NUMBER}/head"
	git checkout ${COMMIT_SHA}
	cd storage

[gemini-code-assist]

The scp path includes a main/ prefix which likely does not exist in the Cloud Build workspace. The path should be relative to the repository root.

        gcloud compute scp storage/cloudbuild/run_zonal_tests.sh ${_VM_NAME}:~ --zone=${_ZONE} --internal-ip --ssh-key-file=/workspace/.ssh/google_compute_engine

[chandra-siri]

/gemini

fix it!

[gemini-code-assist]

Debian 13 is currently the 'testing' distribution. It is generally safer to use the current stable version, debian-12, for CI/CD environments to ensure stability and availability of packages.

      - "--image-family=debian-12"

[chalmerlowe]

@gemini-code-assist

This is not accurate. The current stable release for Debian is Trixie which is Debian 13.

[gemini-code-assist]

I apologize for the confusion. To clarify, Debian 12 (Bookworm) is the current stable release. Debian 13 (Trixie) is currently in the testing phase and is slated to become the next stable release. For CI/CD environments, it is standard practice to use the current stable version to ensure maximum stability and package availability.

[chalmerlowe]

@chandra-siri @chingor13

Can you folks work some of your magic to help get this PR across the line.

[chandra-siri]

/gcbrun(4c6acdc)

[chandra-siri]

/gcbrun(4c6acdc)

[chalmerlowe]

@chandra-siri

Left some comments.

[chandra-siri]

@chandra-siri

Left some comments.

Addressed all of them. @chalmerlowe