winlogbeat: disentangle test data from x-pack/winlogbeat

[efd6]

What does this PR do?

This makes the test data local to the testing code rather than reaching across the
filesystem. Also make some testing helpers more informative.

Why is it important?

The movement of test data in #31817 broke the tests here. This was not discovered until running tests in #31833 due to the non-locality of the data. The duplication of the data here fixes the tests and helps to prevent another case of this kind of breakage.

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.

Author's Checklist

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How to test this PR locally

Related issues

• For [Winlogbeat] add tests for ingest node pipelines #30406

Use cases

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Logs

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Pinging @elastic/security-external-integrations (Team:Security-External Integrations)

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Build stats

• Start Time: 2022-06-08T02:18:34.602+0000

• Duration: 80 min 59 sec

Test stats 🧪

Test	Results
Failed	0
Passed	22257
Skipped	1935
Total	24192

💚 Flaky test report

Tests succeeded.

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