[file] rotator purge fix

[leehinman]

What does this PR do?

In file daily rotator. Previously files that matched the Glob filenamePrefix* were considered rotated files. This change makes it filenamePrefix*.extension.

Why is it important?

With the previous code, files that started with the prefix but ended with a different extension could be considered rotated files and thus available to be purged. For example elastic-agent-diagnostics.zip would be considered a rotated file if the filename prefix was elastic-agent-

Adding the the extension keeps those files from being considered rotated files, and thus out of the list of files that are eligible to be purged.

Checklist

• My code follows the style guidelines of this project
• I have commented my code, particularly in hard-to-understand areas
• I have added tests that prove my fix is effective or that my feature works
• I have added an entry in CHANGELOG.md

Author's Checklist

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Related issues

• Closes Collected diagnostics zip gets removed itself when logging level is set to debug for Windows agent. elastic-agent#3286

[elasticmachine]

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