test: run the bigquery-storage system tests in google cloud build

[danieljbruce]

Description

This pull request adds a yaml file to instruct the Bigquery Storage system test CI check to work with the new Cloud Build trigger thereby making the new CI check effectively run our system tests. It turns out that no extra code modifications are required to allow the test to run in the new environment.

Impact

Leverages the strengths of running system tests in GCB rather than relying on kokoro for system tests.

Testing

This pull request tells the tests how to work with the new check to the continuous integration pipeline for the Bigquery Storage system tests thus improves the effectiveness of that test.

Next Steps

1. Merge a pull request that removes the system tests from kokoro. This should be done in a separate pull request to separate the concerns of removing the kokoro system tests from adding the Google Cloud Build system tests.

[gemini-code-assist]

Code Review

This pull request introduces a Cloud Build configuration (cloudbuild.yaml) for the handwritten/bigquery-storage directory to automate Node.js environment setup, dependency installation, system test execution, and optional code coverage reporting. The reviewer suggested a more robust way to check for and execute the nyc coverage tool using npx --no-install instead of relying on fragile internal paths.

[gemini-code-assist]

Relying on the internal path ./node_modules/nyc/bin/nyc.js is fragile as the internal directory structure of the nyc package is an implementation detail and can change between versions. Using npx --no-install is a more robust and standard way to check for and execute local CLI tools.

    # Check if nyc is installed and run report
    if npx --no-install nyc --version >/dev/null 2>&1; then
      npx nyc report || true
    else
      echo "nyc not found, skipping coverage report."
    fi

[danieljbruce]

As with the other tests, I think it is better here if we stay in alignment with how the kokoro tests worked.