Fix failures in s3-regression-tests in merge queue + fix flakey s3 TM integ test

[alextwoods]

Fix failures in s3-regression-tests in merge queue.

NOTE: To unblock the merge queue, this PR has been merged with #6336

Motivation and Context

check-s3-related-changes: is failing in the merge queue with:

fatal: ambiguous argument 'remotes/origin/refs/heads/master': unknown revision or path not in the working tree.

Example: https://github.com/aws/aws-sdk-java-v2/actions/runs/16947465407/job/48031931821

Modifications

Drops refs/heads/from the ref to prevent the error.

Testing

n/a

Screenshots (if appropriate)

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)

Checklist

• I have read the CONTRIBUTING document
• [] Local run of mvn install succeeds
• My code follows the code style of this project
• My change requires a change to the Javadoc documentation
• I have updated the Javadoc documentation accordingly
• I have added tests to cover my changes
• All new and existing tests passed
• I have added a changelog entry. Adding a new entry must be accomplished by running the scripts/new-change script and following the instructions. Commit the new file created by the script in .changes/next-release with your changes.
• My change is to implement 1.11 parity feature and I have updated LaunchChangelog

License

• I confirm that this pull request can be released under the Apache 2 license

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[github-actions]

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