ci: unique artifact name for junit reports in kind workflow

Due to some recent changes on GitHub's side, uploading the JUnit reports
on the second job to finish in the kind workflow will fail with:

    Error: Failed to CreateArtifact: Received non-retryable error: Failed request: (409) Conflict: an artifact with this name already exists on the workflow run

Avoid this from happing by giving the artifacts unique names.

Fixes #2222

Signed-off-by: Tobias Klauser <[email protected]>

.github/workflows/kind.yaml

@@ -339,7 +339,7 @@ jobs:
         if: ${{ always() }}
         uses: actions/upload-artifact@c7d193f32edcb7bfad88892161225aeda64e9392 # v4.0.0
         with:
-          name: cilium-junits
+          name: cilium-junits-helm-upgrade-clustermesh
           path: cilium-junit*.xml
           retention-days: 2