[ftr] handle unexpected Kibana/ES shutdowns better

[spalger]

Fixes #131522

Adds the ability for the FTR to be notified when ProcRunner or ES Cluster instances exit unexpectedly in the background via a new onEarlyExit() callback passed to these two classes. They both work similarly in that they return promises for a start() function, and then after the tests return a promise for stop(), but in between when the process they monitor exits they both behave differently. ES Cluster's log about the exit, and ProcRunner instances reject a promise which can't be listened to, causing the process to exit. This leads to the problem described in #131522 because when the process it exitted the test runner doesn't get a chance to write the report and devs can't inspect the reasoning for the failure. This changes the behavior to instead inject an error into mocha via runner.uncaught(error) which treats the passed error as an error caused by the current runnable under tests, then runner.abort() is called to stop the tests. This isn't a very clean way to exit, but it still provides the reporting we need to understand what happened.

Confirmed with https://buildkite.com/elastic/kibana-flaky-test-suite-runner/builds/570#_ that Kibana failures which kill the process properly kill the job and trigger a useful report of the test that was running when the failure occurred: https://buildkite.com/organizations/elastic/pipelines/kibana-flaky-test-suite-runner/builds/570/jobs/9e3dbed4-bab9-4513-a9d1-ab372415fdae/artifacts/b5a9f677-8ac8-4f04-9bcd-c989769d4488

[elasticmachine]

Pinging @elastic/kibana-operations (Team:Operations)

[kibana-ci]

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Metrics [docs]

Public APIs missing comments

Total count of every public API that lacks a comment. Target amount is 0. Run node scripts/build_api_docs --plugin [yourplugin] --stats comments for more detailed information.

id	before	after	diff
@kbn/test	198	200	+2

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id	before	after	diff
@kbn/test	236	239	+3

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• 💚 Build #43149 succeeded da5d5af

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[kibanamachine]

💔 All backports failed

Status	Branch	Result
❌	8.2	Backport failed because of merge conflicts
❌	7.17	Backport failed because of merge conflicts You might need to backport the following PRs to 7.17: - Add Playwright Service and New User Journeys for Performance tests (#124259) - [kbn/es] add support for --ready-timeout (#126217)

Manual backport

To create the backport manually run:

node scripts/backport --pr 131767

Questions ?

Please refer to the Backport tool documentation