build UBI s390x nginx package for OSS images

[nginx-bot]

Proposed changes

Similar to PPC64LE architectures, we now need to build s390x packages for UBI images.

Checklist

Before creating a PR, run through this checklist and mark each as complete.

• [x] I have read the CONTRIBUTING doc
• [ ] I have added tests that prove my fix is effective or that my feature works
• [x] I have checked that all unit tests pass after adding my changes
• [x] I have updated necessary documentation
• [x] I have rebased my branch onto main
• [ ] I will ensure my PR is targeting the main branch and pulling from my branch from my own fork

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Please upload report for BASE (release-3.7@eef3176). Learn more about missing BASE report.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## release-3.7 #6847 +/- ## ============================================== Coverage ? 52.97% ============================================== Files ? 85 Lines ? 19764 Branches ? 0 ============================================== Hits ? 10469 Misses ? 8887 Partials ? 408 ```

:umbrella: View full report in Codecov by Sentry.
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