Fix flaky FileIOTest.testMatchWatchForNewFiles test under CI filesystems

[bvolpato]

Please add a meaningful description for your change here

addresses #19480

The FileIOTest.testMatchWatchForNewFiles test occasionally flakes in the CI environment because the updOptions configuration in CopyFilesFn does not preserve file attributes when overwriting existing files. In some CI filesystems, this causes the copied file to register a lastModifiedMillis timestamp of 0. Thus, when ExtractFilenameAndLastUpdateFn parses this file, it throws a RuntimeException at FileIO.java:800, failing the pipeline run.

This PR adds StandardCopyOption.COPY_ATTRIBUTES to preserve the file's original timestamps, avoiding the exception.

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[gemini-code-assist]

Summary of Changes

Hello, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request addresses a flaky test in FileIOTest by ensuring that file attributes are correctly maintained when files are replaced. By preserving original timestamps and increasing the wait time for file operations, the test becomes more resilient to the timing and filesystem constraints often encountered in CI environments.

Highlights

• File Attribute Preservation: Updated the file copy options to include StandardCopyOption.COPY_ATTRIBUTES, ensuring file timestamps are preserved during overwrites to prevent failures in CI environments.
• Test Stability: Increased the Thread.sleep duration from 100ms to 500ms in the test logic to provide more headroom for high-load CI filesystems.

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