ci: introduce sourcegraph-e2e buildkite pipeline
Created by: keegancsmith
We introduce a new Buildkite Pipeline Sourcegraph E2E. This allows us to report E2E results independently on a PR. Currently E2E is run on PRs, but we do not report the failure. This PR leads us to the following improvements:
- Rest of CI returns status faster (E2E is the slowest part of our CI).
- We surface E2E failures, but still allow merging in if it fails.
- One step closer to making our CI pipelines easier to understand.
This PR introduces an async trigger for e2e pipeline from our usual CI pipeline. The trigger is only used in the cases where we soft failed E2E (PRs), otherwise we use the old code paths. If this approach proves successful, we will move to always using the e2e pipeline. We can get the hard failure behaviour by using a sync trigger.
Fixes https://github.com/sourcegraph/sourcegraph/issues/6840