Improve failure reporting output for functional tests

[dej611]

Summary

This PR contains some improvement in case of failures during the functional tests run: in particular when multiple tests are failing the reporter is only showing the number of failures, and to find which test has failed is a process of scrolling the log and look for the "fail" red word.
The alternative method was to use the --bail flag to stop at the first failure.

The improvement in this PR improves the investigation process by integrating the full error message into the custom reporter from mocha and show a short summary of the failures details at the end of the run.
This should simplify the process of debugging failing tests.

• 🐛 Fix log hijack trick to capture mocha error message and format it properly
• 🐛 Fix partial shadowing of test titles for deep nesting suites
• ✨ Add new failures summary at the end of the execution of functional tests
• ✅ Not sure yet how to test the output here

Before

Error inline: mocha was printing the Error breaking the format in the logger as shown below.

Final summary: it shows how many test failed, but not which ones.

After

Error inline: it shows the Error with the right format.

Final summary: after the numbers also details on the name of the failed tests are shown.

Checklist

Delete any items that are not applicable to this PR.

• Unit or functional tests were updated or added to match the most common scenarios

[dej611]

@elasticmachine merge upstream

[kibanamachine]

💚 Build Succeeded

• continuous-integration/kibana-ci/pull-request
• Commit: 5a84415

Build metrics

✅ unchanged

History

• 💔 Build #59401 failed 34d113c
• 💔 Build #59370 failed 24f99ca

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@elasticmachine merge upstream

[spalger]

@dej611 is this ready for review? It's still in draft mode but I'm excited to get it. If you're ready click that "ready for review" button :)

[spalger]

LGTM