fix(data-classes): use user_uid for the Uid in Transfer Family PosixProfile

[LuisFigueroaG]

Issue number: closes #8522

Summary

Changes

build_authentication_response_efs set the PosixProfile Uid to user_gid. It now uses user_uid. Added a test with different uid and gid values, which fails on develop.

User experience

Before: user_gid=1000, user_uid=1001 produced {"Gid": 1000, "Uid": 1000}.
After: it produces {"Gid": 1000, "Uid": 1001}, so EFS users get the configured POSIX user id.

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[boring-cyborg]

Thanks a lot for your first contribution! Please check out our contributing guidelines and don't hesitate to ask whatever you need.
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[leandrodamascena]

Thanks @LuisFigueroaG, nice catch! I was able to reproduce the swapped Uid and confirm the fix across the EFS scenarios, including uid 0, logical home directories and responses with public keys and policy. Approving!

[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

[boring-cyborg]

Awesome work, congrats on your first merged pull request and thank you for helping improve everyone's experience!

[powertools-for-aws-oss-automation]

Awesome work, congrats on your first merged pull request and thank you for helping improve everyone's experience!

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 96.92%. Comparing base (66d3e3b) to head (f1566d1).
⚠️ Report is 1 commits behind head on develop.

Additional details and impacted files

@@           Coverage Diff            @@
##           develop    #8524   +/-   ##
========================================
  Coverage    96.92%   96.92%           
========================================
  Files          317      317           
  Lines        15976    15976           
  Branches      1413     1413           
========================================
  Hits         15484    15484           
  Misses         349      349           
  Partials       143      143           

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