fix(storage): Download Accuracy Fix

[tylerjroach]

• PR title and description conform to Pull Request guidelines.

Issue #, if available:

Description of changes:
Our integration tests occasionally failed with the downloaded file not always matching the expected original. Through logging and file inspections, I was able to determine that in a rapid pause/resume scenario, the DownloadWorker that is cancelled on pause, may still write buffered data to the downloaded file. The new DownloadWorker may have already begun, setting an offset for download that was the file.length at the time. This value may end up being wrong if the previous worker flushes its last bits of data before cancelling. This would result in a section of the file that ends up duplicating contents.

This PR ensures that no buffered data is written to the file once the pause has been initiated.

How did you test these changes?
(Please add a line here how the changes were tested)

Documentation update required?

• No
• Yes (Please include a PR link for the documentation update)

General Checklist

• Added Unit Tests
• Added Integration Tests
• Security oriented best practices and standards are followed (e.g. using input sanitization, principle of least privilege, etc)
• Ensure commit message has the appropriate scope (e.g fix(storage): message, feat(auth): message, chore(all): message)

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[codecov]

Codecov Report

❌ Patch coverage is 28.57143% with 10 lines in your changes missing coverage. Please review.
✅ Project coverage is 54.77%. Comparing base (8b2ef91) to head (82c7600).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #3156   +/-   ##
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  Coverage   54.77%   54.77%           
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  Files        1046     1047    +1     
  Lines       31242    31251    +9     
  Branches     4671     4673    +2     
=======================================
+ Hits        17113    17118    +5     
- Misses      12323    12325    +2     
- Partials     1806     1808    +2     

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[mattcreaser]

Should we also change the ExistingWorkPolicy to REPLACE?

[tylerjroach]

Should we also change the ExistingWorkPolicy to REPLACE?

I didn't see any behavioral difference when testing. I'm guessing this is because we manually cancel the task. Otherwise, it still had the same issue.