Tail-Based sampling test automation script

[bryce-b]

Motivation/summary

This PR introduces a ./cmd/TBS/tbs-testing.py that allows automated testing of the tail-based sampling. The script accepts tail-based sampling configuration parameters, starts the apm-server with that config, generates transactions, and verifies the transactions are properly sampled.

Checklist

• Update CHANGELOG.asciidoc
• error handling around ES json inspection
• Documentation has been update
• add readme.md

How to test these changes

Related issues

#5484

[mergify]

This pull request does not have a backport label. Could you fix it @bryce-b? 🙏
To fixup this pull request, you need to add the backport labels for the needed
branches, such as:

• backport-7.x is the label to automatically backport to the 7.x branch.
• backport-7./d is the label to automatically backport to the 7./d branch. /d is the digit

NOTE: backport-skip has been added to this pull request.

[apmmachine]

💔 Build Failed

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Build stats

• Start Time: 2022-03-17T09:44:39.286+0000

• Duration: 7 min 10 sec

Steps errors

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Run intake

• Took 3 min 25 sec . View more details here
• Description: ./.ci/scripts/intake.sh

🤖 GitHub comments

To re-run your PR in the CI, just comment with:

• /test : Re-trigger the build.

• /hey-apm : Run the hey-apm benchmark.

• /package : Generate and publish the docker images.

• /test windows : Build & tests on Windows.

• run elasticsearch-ci/docs : Re-trigger the docs validation. (use unformatted text in the comment!)

[mergify]

This pull request is now in conflicts. Could you fix it @bryce-b? 🙏
To fixup this pull request, you can check out it locally. See documentation: https://help.github.com/articles/checking-out-pull-requests-locally/

git fetch upstream
git checkout -b tbs-metrics upstream/tbs-metrics
git merge upstream/master
git push upstream tbs-metrics

[simitt]

Thank you for your testing efforts @bryce-b and for sharing your scripts for reproduction. TBS has been released as GA with 8.1. Any further performance tests will be conducted with a new WIP benchmarking approach; closing this PR.