[8.19](backport #44855) Add otelbeat binary for test

[mergify]

Proposed commit message

This PR adds otel test binary that helps us write integration tests close to beats.

Checklist

• My code follows the style guidelines of this project
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have made corresponding change to the default configuration files
• I have added tests that prove my fix is effective or that my feature works
• I have added an entry in CHANGELOG.next.asciidoc or CHANGELOG-developer.next.asciidoc.

How to test this PR locally

cd x-pack/filebeat/
go test -c -tags otelbeat
mage docker:composeUp
go test   -tags "integration otelbeat" -run TestFilebeatOTelE2E ./tests/oteltest -v

Related issues

• Closes https://github.com/elastic/ingest-dev/issues/5689

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This is an automatic backport of pull request #44855 done by [Mergify](https://mergify.com).

[elasticmachine]

Pinging @elastic/elastic-agent-data-plane (Team:Elastic-Agent-Data-Plane)