ci(firestore-bigquery-change-tracker): run offline test suites in CI

[CorieW]

The change tracker's jest suites ran in no CI workflow, so the shared package both the legacy extension and the kit depend on had no regression protection, including the offline tests #2937 added for the insert retry guard. Root jest.config.js only picks up */functions/jest.config.js and gen-schema-view, and nothing invoked the package's test:local.

Most of the tracker's suites create real BigQuery datasets/tables/views or write to a real Firestore, so they can't run on a PR. This adds a CI job that runs the suites that pass without credentials.

Changes

• Add jest.offline.config.js, which reuses jest.config.js and ignores the 11 suites that need a live GCP project.
• Add a test:offline npm script to the tracker package.
• Add a change_tracker job to .github/workflows/test.yml that runs npm ci && npm run test:offline in the package directory.

Verification: npm run test:offline passes, 8 suites / 137 tests in ~43s. The excluded list was determined by running every suite with no credentials, not from the file names, so clustering and checkUpdates are excluded despite the pattern suggested in the issue.

• The exclusion list is a denylist, so a new offline suite is picked up automatically; a new live-project suite must be added to the list.
• Pre-existing Unknown option "types" jest validation warning from jest.config.js is left alone, out of scope.

Fixes #3053

[gemini-code-assist]

Code Review

This pull request introduces an offline Jest configuration (jest.offline.config.js) and a corresponding test:offline script in package.json to run tests that do not require active GCP credentials. The feedback suggests a minor improvement to inherit and extend testPathIgnorePatterns from the base configuration rather than overriding it with a hardcoded array, ensuring better maintainability if the base configuration changes in the future.