Improve Jest tests by showing running test file upon unexpected termination on Jenkins

[watson]

If a Jest test file exists unexpectedly on Jenkins, you don't see which file was running when the program exited:

Please ignore that you, in this case, could inspect the stack trace to gather which test-file was responsible. This isn't always possible due to the async nature of Node.js, or if there isn't any stack trace.

However, if you run the same test locally you'll see a RUNS line:

Here it's easy to see that the unexpected termination happened in src/cli/cluster/cluster_manager.test.ts.

Being able to see this when the tests run in Jenkins would be very helpful and remove a lot of wasted time spent recreating the issue.

[elasticmachine]

Pinging @elastic/kibana-qa (Team:QA)

[elasticmachine]

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

[spalger]

I'd love to fix this but we really have pretty minimal control over how Jest reports things. I think this makes the jest interface ultimately better, but you would probably have better luck reporting this to the Jest project.

[watson]

As far as I understand it, this is configurable by changing or modifying the reporter that we use: https://jestjs.io/docs/en/configuration#reporters-arraymodulename--modulename-options