CI: Merge and Upload Artifacts job

[brlbil]

CI failure

Merge and Upload Artifacts job fails if no artifacts are found. This is not a big problem, but the failed tests show up in workflow status monitor tools and clutter results. There is a PR to the upstream to address this.

Example failure: https://github.com/cilium/cilium/actions/runs/11103779233/job/30848364616 on other runs fails the same way.

Run actions/upload-artifact/merge@50769540e7f4bd5e21e526ee35c689e35e0d6874
  with:
    name: cilium-junits
    pattern: cilium-junits-*
    retention-days: 5
    delete-merged: true
    separate-directories: false
    compression-level: 6
    include-hidden-files: false
  env:
    clusterName: cilium-cilium-11103779[2](https://github.com/cilium/cilium/actions/runs/11103779233/job/30848364616#step:3:2)33-1
    cilium_cli_ci_version: 
    USE_GKE_GCLOUD_AUTH_PLUGIN: true
    gcloud_version: [4](https://github.com/cilium/cilium/actions/runs/11103779233/job/30848364616#step:3:4)94.0.0
Found 0 artifact(s)
Error: No artifacts found matching pattern 'cilium-junits-*'