Enable IBM self-hosted s390x GitHub Actions runners for che-dashboard

[swapnilsingh-ibm]

Is your task related to a problem? Please describe

s390x builds in che-dashboard CI currently use QEMU emulation, which is slower and less reliable than native execution. This causes flaky CI failures and longer build times for s390x architecture jobs.

Describe the solution you'd like

Enable IBM self-hosted s390x GitHub Actions runners for the eclipse-che/che-dashboard repository via the IBM/actionspz service (https://github.com/IBM/actionspz).

Projects need to be reviewed for eligibility before they're on-boarded (we see no problems with che-dashboard in this regard).

You can learn more about the service via our FAQ: https://github.com/IBM/actionspz/blob/main/docs/FAQ.md

Describe alternatives you've considered

No response

Additional context

• s390x support was enabled for che-dashboard and merged in PR - Enable che-dashboard build support on s390x architecture che-dashboard#1595
• IBM's GitHub Actions self-hosted runners are available to use.
• Che Dashboard Reviewer, @akurinnoy, quoted: "QEMU emulation for s390x is significantly slower and less reliable than native execution. If IBM can provide self-hosted s390x runners for GitHub Actions, it would resolve both the build time and flakiness concerns."

[akurinnoy]

@svor please take a look