Add one retry to Ubuntu wait-completion for downstream CI workflow failures

[Copilot]

Description

Bug fixing for Ubuntu_2404 / wait-completion: the job failed immediately when the downstream runner-images-ci workflow returned failure, even for transient breakages. This change adds a single controlled retry in the wait phase before surfacing failure.

• Change summary

  • Updated .github/workflows/trigger-ubuntu-win-build.yml in wait-completion.
  • Passed -MaxRetryCount 1 to helpers/WaitWorkflowCompletion.ps1.
  • Preserves existing terminal behavior: still fails on persistent failure/cancelled/timed_out after retry window.

• Behavioral impact

  • First downstream failure now triggers one rerun of failed jobs.
  • Reduces flaky wait-completion failures without masking persistent regressions.

./helpers/WaitWorkflowCompletion.ps1 `
  -WorkflowRunId "${{ needs.trigger-workflow.outputs.ci_workflow_run_id }}" `
  -Repository "${env:CI_REPO}" `
  -AccessToken "${env:CI_PR_TOKEN}" `
  -MaxRetryCount 1

Related issue:

Ubuntu_2404 / wait-completion failing check run: 81711087502

Check list

• Related issue / work item is attached
• Tests are written (if applicable)
• Documentation is updated (if applicable)
• Changes are tested and related VM images are successfully generated