[quirogas]

Description

This change upgrades CI configurations to Node 22 and isolates unit tests.

Impact

Eliminates EOL Node runtimes in CI and removes external test network calls.

Changes

• Upgrade ci/cloudbuild_with_credentials.yaml from _NODE_VERSION: "18" to "22", add default _REPO_OWNER and _REPO_NAME substitutions, add --pull to docker build, and add id: 'Fetch Credentials' with waitFor: ['Fetch Credentials'] on run-tests to prevent a parallel race condition when writing /workspace/google_application_credentials.json.
• Update the default ARG NODE_VERSION in ci/Dockerfile from 16 to 22, and add --pull to docker build in ci/cloudbuild.yaml and ci/cloudbuild_with_gapic_showcase.yaml.
• Update the Node.js version matrix in .github/workflows/bigtable-conformance.yaml and .github/workflows/mandatory-conformance.yaml from [ 20, 22 ] to [ 22, 24 ].
• Replace unmocked external HTTP calls (http://google.com/ and http://theblahstore) in core/packages/retry-request/test.js with a local ephemeral http.createServer listening on 127.0.0.1:0 so unit tests are 100% hermetic.
• Update remaining .kokoro/**/*.cfg TRAMPOLINE_IMAGE references in core/*/.kokoro/ and handwritten/*/.kokoro/ from node:18-user and node:14-user to node:22-user.

Testing

• Replaced live external requests in core/packages/retry-request/test.js with a local ephemeral HTTP server in before/after hooks (URI_200, URI_404, and URI_NON_EXISTENT).
• Verified all 30 unit tests and gts check linter pass locally in core/packages/retry-request.

Alternatives

• Not merging this PR was considered, but it would leave credentialed Cloud Build triggers and conformance workflows running on EOL Node.js versions and keep retry-request unit tests dependent on external network reachability.

[gemini-code-assist]

Code Review

This pull request upgrades the Node.js version to 22 across Dockerfiles, Cloud Build configurations, and Kokoro CI configurations. Additionally, it refactors the retry-request tests to use a local HTTP server for mocking endpoints instead of external URLs. The review feedback recommends utilizing server.closeAllConnections() in the test teardown to immediately terminate active keep-alive connections and prevent potential hangs.