Upgrade Assistant tests consider ES version in tests

[mshustov]

Describe the feature: We are working on enabling a test scenario when a Kibana instance v7.last is running against Elasticsearch v8.x. This scenario is short-lived and mostly it's needed for the rolling-upgrade cases.
As expected, some UA tests relying on API removed from v8.0 started failing. These failures can cloak real problems, so we need to make sure that UA tests consider the ES version it communicates with:

• it's fine to use deprecated API when running against ES v7.x
• UA shouldn't use deprecated API when running against ES v8.x

[elasticmachine]

Pinging @elastic/platform-deployment-management (Team:Deployment Management)

[cjcenizal]

In #112907 we introduced a UX that prevents users from interacting with the UI during a rolling upgrade. We also wrap each API endpoint in a guard to prevent calling any ES APIs if there's a rolling upgrade.

We have UI tests to verify the UI change, but I think we could also add API integration tests for each endpoint to verify the API guard.

[cjcenizal]

@mshustov What's the priority of this work? Are you actively working on enabling a test scenario when a Kibana instance v7.last is running against Elasticsearch v8.x? If so could you cross-link to any relevant issues or PRs?

[alisonelizabeth]

I have a draft PR up that adds API integration tests based on the discussion in #123063 (comment).

I believe @tylersmalley is working on enabling CI to run Kibana 7.last against Elastic 8.x.

[tylersmalley]

@alisonelizabeth, you can now temporarily test a 7.17 PR against 8.1 by adding the following to .buildkite/scripts/common/env.sh:

export ES_SNAPSHOT_MANIFEST="https://storage.googleapis.com/kibana-ci-es-snapshots-daily/8.1.1/manifest-latest-verified.json" 

(change the version in the manifest URL if needed)

The same thing happens on our nightly forward compatibility tests (which we just resolved a failure with) for 8.0 and 8.1.

Reach out if you have any questions.

[alisonelizabeth]

Fixed via #126524