filestream: fix 'requires pointer' error

[belimawr]

What does this PR do?

This PR fixes the 'requires pointer' error log issued by filestream when a file being harvested is renamed.

Filebeat already recovers from this error by using the file indentifier from the prospector instead of the metadata, so the log message is downgraded to warn and contains more details about what happened.

Why is it important?

It fixes a bug and removes a log error that was somehow misleading.

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

How to test this PR locally

1. Setup filestream to harvest any file
2. Rename the file
3. You should not see any log error

## Related issues
## Use cases
## Screenshots
## Logs

[mergify]

This pull request does not have a backport label.
If this is a bug or security fix, could you label this PR @belimawr? 🙏.
For such, you'll need to label your PR with:

• The upcoming major version of the Elastic Stack
• The upcoming minor version of the Elastic Stack (if you're not pushing a breaking change)

To fixup this pull request, you need to add the backport labels for the needed
branches, such as:

• backport-v8./d.0 is the label to automatically backport to the 8./d branch. /d is the digit

[elasticmachine]

💚 Build Succeeded

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Build stats

• Start Time: 2022-12-13T17:42:23.727+0000

• Duration: 70 min 36 sec

Test stats 🧪

Test	Results
Failed	0
Passed	7161
Skipped	738
Total	7899

💚 Flaky test report

Tests succeeded.

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[elasticmachine]

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

[mergify]

This pull request is now in conflicts. Could you fix it? 🙏
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 fix-filestream-on-remame-meta-error upstream/fix-filestream-on-remame-meta-error
git merge upstream/main
git push upstream fix-filestream-on-remame-meta-error

[mergify]

This pull request is now in conflicts. Could you fix it? 🙏
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 fix-filestream-on-remame-meta-error upstream/fix-filestream-on-remame-meta-error
git merge upstream/main
git push upstream fix-filestream-on-remame-meta-error

[cmacknz]

Thanks for the new tests!

[belimawr]

Folks, I'll take a little longer to merge this PR. I'm not completely happy with my tests, I'm questioning whether I'm just testing a pointer is passed on that method call or I'm testing the correct behaviour/changes in the registry.

I might be going a bit too deep in the rabbit hole here 😅

[sonarcloud]

Kudos, SonarCloud Quality Gate passed!   

0 Bugs
0 Vulnerabilities
0 Security Hotspots
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No Coverage information
1.2% Duplication

[belimawr]

/test