Move pipelines page to GraphQL - Part 8

What does this MR do and why?

Part one: !206072 (merged) ✅

Part two: !207467 (merged) ✅

Part three: !208865 (merged) ✅

Part four: !209348 (merged) ✅

Part five: !210021 (merged) ✅

Part six: !209716 (merged) ✅

Part seven: !210372 (merged) ✅

Part eight: YOU ARE HERE 😄

Goal: Move Build > Pipelines to use GraphQL as the SSOT for data. In part eight we add the subscription implemented in !210777 (merged) to provide realtime pipeline state/statuses to our users.

References

Screenshots or screen recordings

How to set up and validate locally

1. First visit Build > Pipelines and ensure existing feature works as expected.
2. Next enable Feature.enable(:pipelines_page_graphql) && Feature.enable(:ci_pipeline_statuses_updated_subscription) feature flags
3. Visit Build > Pipelines again
4. Trigger changes to pipelines (run, cancel, retry)
5. Ensure statuses reflect true state with subscriptions

Helpful rails console commands

If you don't want to trigger changes in the UI, you can also do this per pipeline in the rails console

pipeline = Ci::Pipeline.find(YOUR_ID)

# Test multiple status changes

pipeline.run!
# Check subscription fired with "running"

pipeline.succeed!
# Check subscription fired with "success"

pipeline.run!
# Check subscription fired again with "running"

pipeline.drop!
# Check subscription fired with "failed"

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.

Related to #223264