Backport 18-9: Set strategy:mirror to propagate downstream failure on check-packages-functionality trigger job

What does this MR do and why?

Describe in detail what merge request is being backported and why

This backports the MR !9238 (merged) that sets strategy:mirror to propagate downstream failure on check-packages-functionality trigger job. This will allow release tooling to detect and surface these failures during RC validations.

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• This MR is backporting a bug fix, documentation update, or spec fix, previously merged in the default branch.
• The original MR has been deployed to GitLab.com (not applicable for documentation or spec changes).
• This MR has a severity label assigned (if applicable).

Note to the merge request author and maintainer

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• Refer to the patch release runbook for engineers and maintainers for guidance.
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