Consolidate E2E coverage and test report collection

What does this MR do and why?

Consolidates E2E coverage and test report collection into a single job and updates coverage export jobs to merge E2E data with unit test data before exporting to ClickHouse.

Background

We collect code coverage data from multiple test suites:

• Unit tests: RSpec (backend), Jest (frontend), Go tests (Workhorse)
• E2E tests: QA specs running against GDK

Previously, E2E coverage was collected by two separate jobs (process-backend-coverage and process-frontend-coverage) in the child pipeline, downloaded by two separate scripts, and the frontend export job was disabled due to pipeline failures.

This MR consolidates everything into a single job and re-enables the frontend coverage export.

Changes

1. Consolidate E2E coverage collection - Merge process-backend-coverage and process-frontend-coverage into single process-e2e-coverage job
2. Consolidate artifact downloads - Single download_e2e_artifacts_from_child_pipeline.rb replaces two separate download scripts
3. Re-enable Jest+E2E export - test-coverage:export-jest-and-e2e job is now functional
4. Add allow_failure: true - Coverage jobs won't block pipelines if they fail
5. Bump test tooling gem - Update to v3.2.0 for responsibility classification support

Artifacts collected by process-e2e-coverage

Directory	Contents
coverage-e2e-backend/	Coverband coverage files
coverage-e2e-frontend/	Istanbul coverage files
e2e-test-mapping/	Backend test-to-source mappings
e2e-test-reports/	RSpec JSON reports with feature_category metadata

Related: gitlab-org/quality/analytics/team#339

References

Screenshots or screen recordings

Before	After

How to set up and validate locally

Validated the consolidated E2E coverage export jobs in https://gitlab.com/gitlab-org/gitlab/-/pipelines/2198843514.

• Backend (RSpec + E2E) job: Successfully merged RSpec and E2E backend coverage, then exported to ClickHouse
• Frontend (Jest + E2E) job: Successfully merged Jest and E2E frontend coverage, then exported to ClickHouse

Pipeline flow validation

The pipeline demonstrates the complete end-to-end flow of collecting, merging, and exporting coverage data:

Step 1: Unit test coverage is collected

The standard coverage jobs run and produce their artifacts:

• rspec:coverage job generates the backend LCOV report and Crystalball test mapping
• coverage-frontend job generates the frontend LCOV report and Jest test mapping

Step 2: E2E tests run with coverage instrumentation

The https://gitlab.com/gitlab-org/gitlab/-/pipelines/2198930464 runs E2E tests with COVERBAND_ENABLED=true and BABEL_ENV=istanbul. After the tests complete, process-e2e-coverage job collects the E2E coverage artifacts (both backend via Coverband and frontend via Istanbul) along with E2E test reports.

Step 3: Coverage and test mappings are merged then exported

The export jobs download artifacts from both the unit test coverage jobs and the consolidated E2E artifacts:

• test-coverage:export-rspec-and-e2e job downloads artifacts from both rspec:coverage and e2e:test-on-gdk, merges the backend LCOV reports, merges the Crystalball and E2E test mappings, then exports the combined data to ClickHouse.
• test-coverage:export-jest-and-e2e job downloads artifacts from both coverage-frontend and e2e:test-on-gdk, merges the frontend LCOV reports, merges the Jest and E2E test mappings, then exports the combined data to ClickHouse.

Both jobs completed successfully, confirming the full pipeline works as expected.

MR acceptance checklist

Evaluate this MR against the MR acceptance checklist. It helps you analyze changes to reduce risks in quality, performance, reliability, security, and maintainability.